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Gray JM, Bossert J, Shyur Y, Saarel B, Briles TC, Lewandowski HJ. Characterization of a vacuum ultraviolet light source at 118 nm. J Chem Phys 2021; 154:024201. [PMID: 33445893 DOI: 10.1063/5.0033135] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Vacuum ultraviolet (VUV) light at 118 nm has been shown to be a powerful tool to ionize molecules for various gas-phase chemical studies. A convenient table top source of 118 nm light can be produced by frequency tripling 355 nm light from a Nd:YAG laser in xenon gas. This process has a low efficiency, typically producing only nJ/pulse of VUV light. Simple models of the tripling process predict that the power of 118 nm light produced should increase quadratically with increasing xenon pressure. However, experimental 118 nm production has been observed to reach a maximum and then decrease to zero with increasing xenon pressure. Here, we describe the basic theory and experimental setup for producing 118 nm light and a new proposed model for the mechanism limiting the production based on pressure broadened absorption.
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Affiliation(s)
- John M Gray
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Jason Bossert
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Yomay Shyur
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Ben Saarel
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Travis C Briles
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - H J Lewandowski
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
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2
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Kilaj A, Gao H, Tahchieva D, Ramakrishnan R, Bachmann D, Gillingham D, von Lilienfeld OA, Küpper J, Willitsch S. Quantum-chemistry-aided identification, synthesis and experimental validation of model systems for conformationally controlled reaction studies: separation of the conformers of 2,3-dibromobuta-1,3-diene in the gas phase. Phys Chem Chem Phys 2020; 22:13431-13439. [PMID: 32515452 DOI: 10.1039/d0cp01396j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The Diels-Alder cycloaddition, in which a diene reacts with a dienophile to form a cyclic compound, counts among the most important tools in organic synthesis. Achieving a precise understanding of its mechanistic details on the quantum level requires new experimental and theoretical methods. Here, we present an experimental approach that separates different diene conformers in a molecular beam as a prerequisite for the investigation of their individual cycloaddition reaction kinetics and dynamics under single-collision conditions in the gas phase. A low- and high-level quantum-chemistry-based screening of more than one hundred dienes identified 2,3-dibromobutadiene (DBB) as an optimal candidate for efficient separation of its gauche and s-trans conformers by electrostatic deflection. A preparation method for DBB was developed which enabled the generation of dense molecular beams of this compound. The theoretical predictions of the molecular properties of DBB were validated by the successful separation of the conformers in the molecular beam. A marked difference in photofragment ion yields of the two conformers upon femtosecond-laser pulse ionization was observed, pointing at a pronounced conformer-specific fragmentation dynamics of ionized DBB. Our work sets the stage for a rigorous examination of mechanistic models of cycloaddition reactions under controlled conditions in the gas phase.
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Affiliation(s)
- Ardita Kilaj
- Department of Chemistry, University of Basel, 4056 Basel, Switzerland.
| | - Hong Gao
- Department of Chemistry, University of Basel, 4056 Basel, Switzerland. and Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China
| | - Diana Tahchieva
- Department of Chemistry, University of Basel, 4056 Basel, Switzerland.
| | - Raghunathan Ramakrishnan
- Department of Chemistry, University of Basel, 4056 Basel, Switzerland. and Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research, Hyderabad 500107, India
| | - Daniel Bachmann
- Department of Chemistry, University of Basel, 4056 Basel, Switzerland.
| | - Dennis Gillingham
- Department of Chemistry, University of Basel, 4056 Basel, Switzerland.
| | - O Anatole von Lilienfeld
- Department of Chemistry, University of Basel, 4056 Basel, Switzerland. and National Center for Computational Design and Discovery of Novel Materials (MARVEL), University of Basel, 4056 Basel, Switzerland
| | - Jochen Küpper
- Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany and Department of Physics, Universität Hamburg, 22761 Hamburg, Germany and Department of Chemistry, Universität Hamburg, 20146 Hamburg, Germany and Center for Ultrafast Imaging, Universität Hamburg, 22761 Hamburg, Germany
| | - Stefan Willitsch
- Department of Chemistry, University of Basel, 4056 Basel, Switzerland.
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Owusu-Ansah E, Rajendran A, Shi Y. Catalytic dissociation of tris(dimethylamino)silane on hot tungsten and tantalum filament surfaces. Phys Chem Chem Phys 2019; 21:14357-14365. [PMID: 30714585 DOI: 10.1039/c8cp06669h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The dissociation of tris(dimethylamino)silane (TrDMAS) on hot tungsten and tantalum surfaces was studied under collision-free conditions. The products from the hot-wire decomposition of TrDMAS were monitored using a 10.5 eV vacuum ultraviolet laser single-photon ionization in tandem with time-of-flight mass spectrometry. Formation of a methyl radical and N-methyl methyleneimine (NMMI) was detected. A transition from a surface reaction rate-limiting regime at filament temperatures lower than 1800-2000 °C to mass transport regime at higher temperatures (>1800-2000 °C) was observed for the formation of both products. In the surface reaction regime, the Arrhenius behavior was followed in two separate temperature regions with different activation energies. It was found that low temperatures (900-1300 °C) favor the production of the methyl radical and high temperatures (1400-2000 °C) favor the production of NMMI with lower activation energies. A theoretical investigation using ab initio calculations of the concerted and stepwise formation of NMMI along with the homolytic cleavages of N-CH3 and Si-H in the gas phase has shown that the concerted pathway to form NMMI is the most energetically favorable one of all four routes with an activation barrier of 328 kJ mol-1. The lower activation energy values determined experimentally for the formation of NMMI and ˙CH3 as compared to those obtained from theoretical calculations indicate that the dissociation of TrDMAS, an N-containing organosilicon molecule, on the W and Ta surfaces is a catalytic cracking process.
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Affiliation(s)
- Ebenezer Owusu-Ansah
- Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4.
| | - Arun Rajendran
- Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4.
| | - Yujun Shi
- Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4.
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Song WT, Hu YJ, Jin S, Li YJ. Dissociative photoionization of heterocyclic molecule-morpholine under VUV synchrotron radiation. CHINESE J CHEM PHYS 2019. [DOI: 10.1063/1674-0068/cjcp1904068] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Wen-tao Song
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, and Guangzhou Key Laboratory of spectral analysis and functional probes, College of Biophotonics, South China Normal University, Guangzhou 510631, China
| | - Yong-jun Hu
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, and Guangzhou Key Laboratory of spectral analysis and functional probes, College of Biophotonics, South China Normal University, Guangzhou 510631, China
| | - Shan Jin
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, and Guangzhou Key Laboratory of spectral analysis and functional probes, College of Biophotonics, South China Normal University, Guangzhou 510631, China
| | - Yu-jian Li
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, and Guangzhou Key Laboratory of spectral analysis and functional probes, College of Biophotonics, South China Normal University, Guangzhou 510631, China
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5
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Theoretical study of transesterification of diethyl carbonate with methanol catalyzed by base and Lewis acid. Theor Chem Acc 2019. [DOI: 10.1007/s00214-018-2411-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Insight into the mechanism of the catalysis of urethane formation by organotin(IV) dicarboxylate. REACTION KINETICS MECHANISMS AND CATALYSIS 2018. [DOI: 10.1007/s11144-018-1366-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Jin S, Hu Y, Wang P, Zhan H, Lu Q, Liu F, Sheng L. Hydrogen bonding and dominant conformations of hydrated sugar analogue complexes using tetrahydrofurfuryl alcohol as the model sugar molecule. Phys Chem Chem Phys 2018; 20:7351-7360. [DOI: 10.1039/c7cp07935d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Water molecules, which serve as both hydrogen bond donors and acceptors, have been found to influence the conformational landscape of gas-phase phenyl-β-d-glucopyranoside.
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Affiliation(s)
- Shan Jin
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science
- College of Biophotonics
- South China Normal University
- Guangzhou 510631
- P. R. China
| | - Yongjun Hu
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science
- College of Biophotonics
- South China Normal University
- Guangzhou 510631
- P. R. China
| | - Pengchao Wang
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science
- College of Biophotonics
- South China Normal University
- Guangzhou 510631
- P. R. China
| | - Huaqi Zhan
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science
- College of Biophotonics
- South China Normal University
- Guangzhou 510631
- P. R. China
| | - Qiao Lu
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science
- College of Biophotonics
- South China Normal University
- Guangzhou 510631
- P. R. China
| | - Fuyi Liu
- National Synchrotron Radiation Laboratory
- University of Science and Technology of China
- Hefei
- P. R. China
| | - Liusi Sheng
- National Synchrotron Radiation Laboratory
- University of Science and Technology of China
- Hefei
- P. R. China
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Badran I, Shi Y. A kinetic study of the gas-phase reactions of 1-methylsilacyclobutane in hot wire chemical vapor deposition. Phys Chem Chem Phys 2017; 20:75-85. [PMID: 29170772 DOI: 10.1039/c7cp06082c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reaction kinetics of the decomposition of 1-methylsilacyclobutane (MSCB) in a hot wire chemical vapor deposition (HWCVD) reactor was investigated. The stable reaction products were monitored using vacuum ultraviolet laser single photon ionization in tandem with time-of-flight mass spectrometry. Steady-state approximation was used to determine the rate constants of three individual decomposition pathways of MSCB, i.e., cycloreversion to form ethene and methylsilene (R1), ring opening to form propene and methylsilylene (R2), and exocyclic Si-CH3 bond cleavage to form ˙CH3 radicals (R3). The activation energies (Ea) for R2 and R3 in a HWCVD reactor were determined to be 86.6 kJ mol-1 and 106 kJ mol-1, respectively. The fact that these Ea values are close to those obtained for the MSCB decomposition on metal surfaces under collision-free conditions indicates that the heterogeneous reactions on the hot wire surface govern the gas-phase reaction kinetics in the HWCVD reactor. In addition, the Ea values obtained from a theoretical study of the decomposition kinetics using ab initio calculations at the CCSD(T)/6-311++G(3d,2p)//MP2/6-311++G(d,p) level were 62.9 kcal mol-1 (i.e., 263 kJ mol-1), 62.0 kcal mol-1 (i.e., 259 kJ mol-1), and 86.2 kcal mol-1 (i.e., 361 kJ mol-1) for R1, R2, and R3, respectively. The much lower experimental Ea values compared with those from the theoretical calculations clearly suggest that the tungsten filament in the HWCVD reactor catalyzed the decomposition.
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Affiliation(s)
- Ismail Badran
- Department of Chemistry, University of Calgary, Calgary, Alberta T2N 1N4, Canada.
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Shin JW, Bernstein ER. IR + VUV double resonance spectroscopy and extended density functional theory studies of ketone solvation by alcohol: 2-butanone·(methanol) n, n = 1–4 clusters. J Chem Phys 2017; 147:124311. [DOI: 10.1063/1.4995997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Joong-Won Shin
- Division of Science, Mathematics, and Technology, Governors State University, University Park, Illinois 60484-0975, USA
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
| | - Elliot R. Bernstein
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
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Zhao Z, Kobayashi Y. Realization of a mW-level 10.7-eV (λ = 115.6 nm) laser by cascaded third harmonic generation of a Yb:fiber CPA laser at 1-MHz. OPTICS EXPRESS 2017; 25:13517-13526. [PMID: 28788895 DOI: 10.1364/oe.25.013517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 05/31/2017] [Indexed: 06/07/2023]
Abstract
We demonstrate a 10.7-eV (λ = 115.6 nm) laser with mW levels of average power and a 1-MHz repetition rate, which was driven by the third harmonic radiation (THG), at 347 nm, of an Yb:fiber chirped pulse amplifier (CPA) laser. The 347 nm ultraviolet radiation was obtained by frequency conversion of the high power output of a 1-MHz Yb:fiber CPA, using beta barium borate (BBO) nonlinear crystals. The frequency converted output was focused down into a gas cell filled with a mixture of Ar and Xe, and was subjected to a second THG frequency conversion. The generated 10.7-eV laser was separated from the fundamental beam using a LiF prism and no further separation from other harmonic waves was required. The highest measured output power was ~80 μW, which corresponded to an average power of ~1.25 mW inside the gas cell when the transmission coefficients of the LiF optics were taken into account. The corresponding conversion efficiency from 347 nm down to 115.6 nm was ~2.5 × 10-4.
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Zhan H, Hu Y, Wang P, Chen J. Dominant conformer of tetrahydropyran-2-methanol and its clusters in the gas phase explored by the use of VUV photoionization and vibrational spectroscopy. J Chem Phys 2017; 146:134303. [DOI: 10.1063/1.4979298] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Affiliation(s)
- Huaqi Zhan
- MOE Key laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, People’s Republic of China
| | - Yongjun Hu
- MOE Key laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, People’s Republic of China
| | - Pengchao Wang
- MOE Key laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, People’s Republic of China
| | - Jiaxin Chen
- MOE Key laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510631, People’s Republic of China
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12
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Shin JW, Bernstein ER. Vacuum ultraviolet photoionization of carbohydrates and nucleotides. J Chem Phys 2015; 140:044330. [PMID: 25669546 DOI: 10.1063/1.4862829] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Carbohydrates (2-deoxyribose, ribose, and xylose) and nucleotides (adenosine-, cytidine-, guanosine-, and uridine-5(')-monophosphate) are generated in the gas phase, and ionized with vacuum ultraviolet photons (VUV, 118.2 nm). The observed time of flight mass spectra of the carbohydrate fragmentation are similar to those observed [J.-W. Shin, F. Dong, M. Grisham, J. J. Rocca, and E. R. Bernstein, Chem. Phys. Lett. 506, 161 (2011)] for 46.9 nm photon ionization, but with more intensity in higher mass fragment ions. The tendency of carbohydrate ions to fragment extensively following ionization seemingly suggests that nucleic acids might undergo radiation damage as a result of carbohydrate, rather than nucleobase fragmentation. VUV photoionization of nucleotides (monophosphate-carbohydrate-nucleobase), however, shows that the carbohydrate-nucleobase bond is the primary fragmentation site for these species. Density functional theory (DFT) calculations indicate that the removed carbohydrate electrons by the 118.2 nm photons are associated with endocyclic C-C and C-O ring centered orbitals: loss of electron density in the ring bonds of the nascent ion can thus account for the observed fragmentation patterns following carbohydrate ionization. DFT calculations also indicate that electrons removed from nucleotides under these same conditions are associated with orbitals involved with the nucleobase-saccharide linkage electron density. The calculations give a general mechanism and explanation of the experimental results.
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Affiliation(s)
- Joong-Won Shin
- Division of Science, Governors State University, University Park, Illinois 60484-0975, USA
| | - Elliot R Bernstein
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
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Braud I, Boulon J, Zamith S, L’Hermite JM. Attachment of Water and Alcohol Molecules onto Water and Alcohol Clusters. J Phys Chem A 2015; 119:6017-23. [DOI: 10.1021/jp511854r] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Isabelle Braud
- Laboratoire Collisions Agrégats
Réactivité, IRSAMC, Université de Toulouse, UPS, F-31062 Toulouse, France
- CNRS, UMR 5589, F-31062 Toulouse, France
| | - Julien Boulon
- Laboratoire Collisions Agrégats
Réactivité, IRSAMC, Université de Toulouse, UPS, F-31062 Toulouse, France
- CNRS, UMR 5589, F-31062 Toulouse, France
| | - Sébastien Zamith
- Laboratoire Collisions Agrégats
Réactivité, IRSAMC, Université de Toulouse, UPS, F-31062 Toulouse, France
- CNRS, UMR 5589, F-31062 Toulouse, France
| | - Jean-Marc L’Hermite
- Laboratoire Collisions Agrégats
Réactivité, IRSAMC, Université de Toulouse, UPS, F-31062 Toulouse, France
- CNRS, UMR 5589, F-31062 Toulouse, France
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Shi Y. Hot wire chemical vapor deposition chemistry in the gas phase and on the catalyst surface with organosilicon compounds. Acc Chem Res 2015; 48:163-73. [PMID: 25586211 DOI: 10.1021/ar500241x] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
CONSPECTUS: Hot wire chemical vapor deposition (HWCVD), also referred to as catalytic CVD (Cat-CVD), has been used to produce Si-containing thin films, nanomaterials, and functional polymer coatings that have found wide applications in microelectronic and photovoltaic devices, in automobiles, and in biotechnology. The success of HWCVD is largely due to its various advantages, including high deposition rate, low substrate temperatures, lack of plasma-induced damage, and large-area uniformity. Film growth in HWCVD is induced by reactive species generated from primary decomposition on the metal wire or from secondary reactions in the gas phase. In order to achieve a rational and efficient optimization of the process, it is essential to identify the reactive species and to understand the chemical kinetics that govern the production of these precursor species for film growth. In this Account, we report recent progress in unraveling the complex gas-phase reaction chemistry in the HWCVD growth of silicon carbide thin films using organosilicon compounds as single-source precursors. We have demonstrated that laser ionization mass spectrometry is a powerful diagnostic tool for studying the gas-phase reaction chemistry when combined with the methods of isotope labeling and chemical trapping. The four methyl-substituted silane molecules, belonging to open-chain alkylsilanes, dissociatively adsorb on W and Ta filaments to produce methyl radical and H2 molecule. Under the typical deposition pressures, with increasing number of methyl substitution, the dominant chemistry occurring in the gas phase switches from silylene/silene reactions to free-radical short chain reactions. This change in dominant reaction intermediates from silylene/silene to methyl radicals explains the observation from thin film deposition that silicon carbide films become more C-rich with a decreasing number of Si-H bonds in the four precursor molecules. In the case of cyclic monosilacyclobutanes, we have shown that ring-opening reactions play a vital role in characterizing the reaction chemistry. On the other hand, exocyclic Si-H(CH3) bond cleavages are more important in the less-puckered disilacyclobutane molecules. Metal filaments are essential in HWCVD since they serve as catalysts to decompose precursor gases to reactive species, which initiate gas-phase reaction chemistry and thin film growth. We discuss the structural changes in metal filaments when exposed to various precursor gases. Depending on the nature of the radical intermediates formed from the hot-wire decomposition and subsequent gas-phase reactions, metal silicides and carbides can be formed. Overall, study of the gas-phase reaction chemistry in HWCVD provides important knowledge of the chemical species produced prior to their deposition on a substrate surface. This helps in identifying the major contributor to alloy formation on the filament itself and the film growth, and consequently, in determining the properties of the deposited films. An integrated knowledge of the gas-phase reaction chemistry, filament alloy formation, and thin film deposition is required for an efficient deposition of high-quality thin films and nanomaterials.
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Affiliation(s)
- Yujun Shi
- Department of Chemistry, University of Calgary, Calgary, Alberta T2N 1N4, Canada
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Badran I, Shi YJ. Promotion of exocyclic bond cleavages in the decomposition of 1,3-disilacyclobutane in the presence of a metal filament. J Phys Chem A 2015; 119:590-600. [PMID: 25560235 DOI: 10.1021/jp511716x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The primary decomposition of 1,3-disilacyclobutane (DSCB) on a tungsten filament and its secondary gas-phase reactions in a hot-wire chemical vapor deposition (CVD) reactor have been studied using laser ionization mass spectrometry. Under the collision-free conditions, DSCB decomposes on the W filament to produce H2 molecules with an activation energy of 43.6 ± 4.1 kJ·mol(-1). With the help of the isotope labeling and chemical trapping methods, the mechanistic details in the secondary gas-phase reactions important in the hot-wire CVD reactor setup have been examined. The dominant pathway has been demonstrated to be the insertion of the cyclic 1,3-disilacyclobut-1-ylidene, generated by exocyclic Si-H bond rupture, into the Si-H bond in DSCB to form 1,1'-bis(1,3-disilacyclobutane) (174 amu). The successful trapping of 1,3-disilacyclobut-1-ylidene by both 1,3-butadiene and trimethylsilane provides compelling evidence for the existence of this cyclic silylene species in the hot-wire CVD reactor with DSCB. Other reactions operating in the reactor include the DSCB cycloreversion to form silene and the ring opening of DSCB via 1,2-H shift to produce silene/methylsilylene and 1-methylsilene/silylene. The introduction of an additional Si atom in the four-membered ring monosilacyclobutane molecule has caused two major changes in the reaction chemistry assumed by DSCB: (1) The endocyclic cycloreversion reactions that dominate in the decomposition of monosilacyclobutane molecules only play a much less important role in the dissociation of DSCB; and (2) the exocyclic bond cleavages are promoted in DSCB due to the ring stabilization caused by the introduction of one additional Si atom.
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Affiliation(s)
- I Badran
- Department of Chemistry, University of Calgary , Calgary, Alberta T2N 1 N4, Canada
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Maity S, Kaiser RI, Jones BM. Formation of complex organic molecules in methanol and methanol-carbon monoxide ices exposed to ionizing radiation--a combined FTIR and reflectron time-of-flight mass spectrometry study. Phys Chem Chem Phys 2014; 17:3081-114. [PMID: 25515545 DOI: 10.1039/c4cp04149f] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The radiation induced chemical processing of methanol and methanol-carbon monoxide ices at 5.5 K exposed to ionizing radiation in the form of energetic electrons and subsequent temperature programmed desorption is reported in this study. The endogenous formation of complex organic molecules was monitored online and in situ via infrared spectroscopy in the solid state and post irradiation with temperature programmed desorption (TPD) using highly sensitive reflectron time-of-flight (ReTOF) mass spectrometry coupled with single photoionization at 10.49 eV. Infrared spectroscopic analysis of the processed ice systems resulted in the identification of simple molecules including the hydroxymethyl radical (CH2OH), formyl radical (HCO), methane (CH4), formaldehyde (H2CO), carbon dioxide (CO2), ethylene glycol (HOCH2CH2OH), glycolaldehyde (HOCH2CHO), methyl formate (HCOOCH3), and ketene (H2CCO). In addition, ReTOF mass spectrometry of subliming molecules following temperature programmed desorption definitely identified several closed shell C/H/O bearing organics including ketene (H2CCO), acetaldehyde (CH3COH), ethanol (C2H5OH), dimethyl ether (CH3OCH3), glyoxal (HCOCOH), glycolaldehyde (HOCH2CHO), ethene-1,2-diol (HOCHCHOH), ethylene glycol (HOCH2CH2OH), methoxy methanol (CH3OCH2OH) and glycerol (CH2OHCHOHCH2OH) in the processed ice systems. Additionally, an abundant amount of molecules yet to be specifically identified were observed sublimating from the irradiated ices including isomers with the formula C3H(x=4,6,8)O, C4H(x=8,10)O, C3H(x=4,6,8)O2, C4H(x=6,8)O2, C3H(x=4,6)O3, C4H8O3, C4H(x=4,6,8)O4, C5H(x=6,8)O4 and C5H(x=6,8)O5. The last group of molecules containing four to five oxygen atoms observed sublimating from the processed ice samples include an astrobiologically important class of sugars relevant to RNA, phospholipids and energy storage. Experiments are currently being designed to elucidate their chemical structure. In addition, several reaction pathways were identified in the irradiated ices of mixed isotopes based upon the results of both in situ FTIR analysis and TPD ReTOF gas phase analysis. In general, the results of this study provide crucial information on the formation of a variety of classes of organics including alcohols, ketones, aldehydes, esters, ethers, and sugars within the bulk ices upon exposure to ionizing radiation that are relevant to the molecular clouds within the interstellar medium.
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Affiliation(s)
- Surajit Maity
- Department of Chemistry, W.M. Keck Research Laboratory in Astrochemistry, University of Hawai'i at Manoa, Honolulu, HI 96822, USA.
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Samuilov AY, Nesterov SV, Balabanova FB, Samuilov YD, Konovalov AI. Quantum-chemical study of isocyanate reactions with linear methanol associates: IX. Methyl isocyanate reaction with methanol-phenol complexes. RUSSIAN JOURNAL OF ORGANIC CHEMISTRY 2014. [DOI: 10.1134/s1070428014020018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Toukabri R, Shi Y. Unraveling the complex chemistry using dimethylsilane as a precursor gas in hot wire chemical vapor deposition. Phys Chem Chem Phys 2014; 16:7896-906. [DOI: 10.1039/c4cp00275j] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
At low filament temperatures and short reaction time, silylene chemistry dominates. The free-radical reactions become more important with increasing temperature and time.
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Affiliation(s)
- Rim Toukabri
- Department of Chemistry
- University of Calgary
- Calgary, T2N 1N4 Canada
| | - Yujun Shi
- Department of Chemistry
- University of Calgary
- Calgary, T2N 1N4 Canada
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19
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Hu Y, Guan J, Bernstein ER. Mass-selected IR-VUV (118 nm) spectroscopic studies of radicals, aliphatic molecules, and their clusters. MASS SPECTROMETRY REVIEWS 2013; 32:484-501. [PMID: 24122973 DOI: 10.1002/mas.21387] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 04/25/2013] [Accepted: 04/25/2013] [Indexed: 06/02/2023]
Abstract
Mass-selected IR plus UV/VUV spectroscopy and mass spectrometry have been coupled into a powerful technique to investigate chemical, physical, structural, and electronic properties of radicals, molecules, and clusters. Advantages of the use of vacuum ultraviolet (VUV) radiation to create ions for mass spectrometry are its application to nearly all compounds with ionization potentials below the energy of a single VUV photon, its circumventing the requirement of UV chromophore group, its inability to ionize background gases, and its greatly reduced fragmenting capabilities. In this review, mass-selected IR plus VUV (118 nm) spectroscopy is introduced first in a general manner. Selected application examples of this spectroscopy are presented, which include the detections and structural analysis of radicals, molecules, and molecular clusters in a supersonic jet.
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Affiliation(s)
- Yongjun Hu
- MOE Key Laboratory of Laser Life Science & Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou, 510631, China
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20
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Toukabri R, Alkadhi N, Shi YJ. Formation of Methyl Radicals from Decomposition of Methyl-Substituted Silanes over Tungsten and Tantalum Filament Surfaces. J Phys Chem A 2013; 117:7697-704. [DOI: 10.1021/jp404882t] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- R. Toukabri
- Department of Chemistry, University of Calgary, Calgary, Alberta,
Canada T2N 1N4
| | - N. Alkadhi
- Department of Chemistry, University of Calgary, Calgary, Alberta,
Canada T2N 1N4
| | - Y. J. Shi
- Department of Chemistry, University of Calgary, Calgary, Alberta,
Canada T2N 1N4
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21
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Li W, Hu Y, Guan J, Liu F, Shan X, Sheng L. Site-selective ionization of ethanol dimer under the tunable synchrotron VUV radiation and its subsequent fragmentation. J Chem Phys 2013; 139:024307. [DOI: 10.1063/1.4812780] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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22
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Guan J, Hu Y, Zou H, Cao L, Liu F, Shan X, Sheng L. Competitive fragmentation pathways of acetic acid dimer explored by synchrotron VUV photoionization mass spectrometry and electronic structure calculations. J Chem Phys 2012; 137:124308. [DOI: 10.1063/1.4754273] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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23
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Badran I, Forster TD, Roesler R, Shi YJ. Competition of Silene/Silylene Chemistry with Free Radical Chain Reactions Using 1-Methylsilacyclobutane in the Hot-Wire Chemical Vapor Deposition Process. J Phys Chem A 2012; 116:10054-62. [DOI: 10.1021/jp3055558] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- I. Badran
- Department of Chemistry, University of Calgary, Calgary, Alberta
T2N 1N4, Canada
| | - T. D. Forster
- Department of Chemistry, University of Calgary, Calgary, Alberta
T2N 1N4, Canada
| | - R. Roesler
- Department of Chemistry, University of Calgary, Calgary, Alberta
T2N 1N4, Canada
| | - Y. J. Shi
- Department of Chemistry, University of Calgary, Calgary, Alberta
T2N 1N4, Canada
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24
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Tamenori Y, Okada K, Tabayashi K, Hiraya A, Gejo T, Honma K. Photodissociation investigation of doubly charged ethanol clusters induced by inner-shell electron ionization. J Chem Phys 2011; 134:204302. [DOI: 10.1063/1.3590164] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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25
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Han HL, Camacho C, Witek HA, Lee YP. Infrared absorption of methanol clusters (CH3OH)n with n = 2−6 recorded with a time-of-flight mass spectrometer using infrared depletion and vacuum-ultraviolet ionization. J Chem Phys 2011; 134:144309. [DOI: 10.1063/1.3572225] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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26
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27
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Marksteiner M, Haslinger P, Sclafani M, Ulbricht H, Arndt M. UV and VUV Ionization of Organic Molecules, Clusters, and Complexes. J Phys Chem A 2009; 113:9952-7. [DOI: 10.1021/jp905039f] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Markus Marksteiner
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
| | - Philipp Haslinger
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
| | - Michele Sclafani
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
| | - Hendrik Ulbricht
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
| | - Markus Arndt
- Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria
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28
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Shin JW, Bernstein ER. Experimental and theoretical studies of isolated neutral and ionic 2-propanol and their clusters. J Chem Phys 2009; 130:214306. [DOI: 10.1063/1.3148378] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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29
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Liu Y, Consta S, Shi Y, Lipson RH, Goddard WA. Prediction of the Size Distributions of Methanol−Ethanol Clusters Detected in VUV Laser/Time-of-Flight Mass Spectrometry. J Phys Chem A 2009; 113:6865-75. [DOI: 10.1021/jp900487x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Yi Liu
- Materials and Process Simulation Center (M/C 139-74), California Institute of Technology, 1200 East California Boulevard., Pasadena, California, 91125, Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5B7, and Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Styliani Consta
- Materials and Process Simulation Center (M/C 139-74), California Institute of Technology, 1200 East California Boulevard., Pasadena, California, 91125, Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5B7, and Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - Yujun Shi
- Materials and Process Simulation Center (M/C 139-74), California Institute of Technology, 1200 East California Boulevard., Pasadena, California, 91125, Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5B7, and Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - R. H. Lipson
- Materials and Process Simulation Center (M/C 139-74), California Institute of Technology, 1200 East California Boulevard., Pasadena, California, 91125, Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5B7, and Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
| | - William A. Goddard
- Materials and Process Simulation Center (M/C 139-74), California Institute of Technology, 1200 East California Boulevard., Pasadena, California, 91125, Department of Chemistry, The University of Western Ontario, London, Ontario, Canada N6A 5B7, and Department of Chemistry, University of Calgary, Calgary, Alberta, Canada T2N 1N4
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30
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Hajgató B, Deleuze MS, Morini F. Probing Nuclear Dynamics in Momentum Space: A New Interpretation of (e, 2e) Electron Impact Ionization Experiments on Ethanol. J Phys Chem A 2009; 113:7138-54. [DOI: 10.1021/jp9027029] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Balázs Hajgató
- Research Group of Theoretical Chemistry, Department SBG, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium, and Eenheid Algemene Chemie, Vrije Universiteit Brussel, Faculteit Wetenschappen, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Michael S. Deleuze
- Research Group of Theoretical Chemistry, Department SBG, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium, and Eenheid Algemene Chemie, Vrije Universiteit Brussel, Faculteit Wetenschappen, Pleinlaan 2, B-1050 Brussels, Belgium
| | - Filippo Morini
- Research Group of Theoretical Chemistry, Department SBG, Hasselt University, Agoralaan Gebouw D, B-3590 Diepenbeek, Belgium, and Eenheid Algemene Chemie, Vrije Universiteit Brussel, Faculteit Wetenschappen, Pleinlaan 2, B-1050 Brussels, Belgium
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31
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Sakai D, Matsuda Y, Hachiya M, Mori M, Fujii A, Mikami N. Size-Selected Infrared Predissociation Spectroscopy of Neutral and Cationic Formamide−Water Clusters: Stepwise Growth of Hydrated Structures and Intracluster Hydrogen Transfer Induced by Vacuum-Ultraviolet Photoionization. J Phys Chem A 2008; 112:6840-9. [DOI: 10.1021/jp800743b] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Daichi Sakai
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki-Aoba, Aoba-ku, Sendai 980-8578, Japan
| | - Yoshiyuki Matsuda
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki-Aoba, Aoba-ku, Sendai 980-8578, Japan
| | - Masaki Hachiya
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki-Aoba, Aoba-ku, Sendai 980-8578, Japan
| | - Mayumi Mori
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki-Aoba, Aoba-ku, Sendai 980-8578, Japan
| | - Asuka Fujii
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki-Aoba, Aoba-ku, Sendai 980-8578, Japan
| | - Naohiko Mikami
- Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki-Aoba, Aoba-ku, Sendai 980-8578, Japan
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32
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Kostko O, Belau L, Wilson KR, Ahmed M. Vacuum-Ultraviolet (VUV) Photoionization of Small Methanol and Methanol−Water Clusters. J Phys Chem A 2008; 112:9555-62. [DOI: 10.1021/jp8020479] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Oleg Kostko
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Leonid Belau
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Kevin R. Wilson
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
| | - Musahid Ahmed
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720
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33
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Yang J, Wang XB, Xing XP, Wang LS. Photoelectron spectroscopy of anions at 118.2nm: Observation of high electron binding energies in superhalogens MCl4− (M=Sc, Y, La). J Chem Phys 2008; 128:201102. [DOI: 10.1063/1.2938390] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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34
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Tamenori Y, Okada K, Takahashi O, Arakawa S, Tabayashi K, Hiraya A, Gejo T, Honma K. Hydrogen bonding in methanol clusters probed by inner-shell photoabsorption spectroscopy in the carbon and oxygen K-edge regions. J Chem Phys 2008; 128:124321. [DOI: 10.1063/1.2898536] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
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35
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Hachiya M, Matsuda Y, Suhara KI, Mikami N, Fujii A. Infrared predissociation spectroscopy of cluster cations of protic molecules, (NH[sub 3])[sub n]+], n=2–4 and (CH[sub 3]OH)[sub n]+], n=2,3. J Chem Phys 2008; 129:094306. [DOI: 10.1063/1.2971186] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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36
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Nedić M, Wassermann TN, Xue Z, Zielke P, Suhm MA. Raman spectroscopic evidence for the most stable water/ethanol dimer and for the negative mixing energy in cold water/ethanol trimers. Phys Chem Chem Phys 2008; 10:5953-6. [DOI: 10.1039/b811154e] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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37
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Eustergerling B, Hèden M, Shi Y. Application of laser induced electron impact ionization to the deposition chemistry in the hot-wire chemical vapor deposition process with SiH4-NH3 gas mixtures. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2007; 18:1950-8. [PMID: 17869128 DOI: 10.1016/j.jasms.2007.08.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2007] [Revised: 08/21/2007] [Accepted: 08/21/2007] [Indexed: 05/17/2023]
Abstract
The application of a laser-induced electron impact (LIEI) ionization source in studying the gas-phase chemistry of the SiH(4)/NH(3) hot-wire chemical vapor deposition (HWCVD) system has been investigated. The LIEI source is achieved by directing an unfocused laser beam containing both 118 nm (10.5 eV) vacuum ultraviolet (VUV) and 355 nm UV radiations to the repeller plate in a time-of-flight mass spectrometer. Comparison of the LIEI source with the conventional 118 nm VUV single-photon ionization (SPI) method has demonstrated that the intensities of the chemical species with ionization potentials (IP) above 10.5 eV, e.g., H(2), N(2) and He, have been significantly enhanced with the incorporation of the LIEI source. It is found that the SPI source due to the 118 nm VUV light coexists in the LIEI source. This allows simultaneous observations of parent ions with enhanced intensity from VUV SPI and their "fingerprint" fragmentation ions from LIEI. It is, therefore, an effective tool to diagnose the gas-phase chemical species involved with both NH(3) and SiH(4) in the HWCVD reactor. In using the LIEI source to SiH(4), NH(3) and their mixtures, it has been shown that the NH(3) decomposition is suppressed with the addition of SiH(4) molecules. Examination of the NH(3) decomposition percentage and the time to reach the N(2) and H(2) steady-state intensities for various NH(3)/SiH(4) mixtures suggests that the extent of the suppression is enhanced with more SiH(4) content in the mixture. With increasing filament temperatures, the negative effect of SiH(4) becomes less important.
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38
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Liu Y, Consta S, Ogeer F, Shi YJ, Lipson RH. Geometries and energetics of methanol–ethanol clusters: a VUV laser/time-of-flight mass spectrometry and density functional theory study. CAN J CHEM 2007. [DOI: 10.1139/v07-104] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Hydrogen-bonded clusters, formed above liquid methanol (Me) and ethanol (Et) mixtures of various compositions, were entrained in a supersonic jet and probed using 118 nm vacuum ultraviolet (VUV) laser single-photon ionization/time-of-flight mass spectrometry. The spectra are dominated by protonated cluster ions, formed by ionizing hydrogen-bonded MemEtn neutrals, m = 0–4, n = 0–3, and m + n = 2–5. The structures and energetics of the neutral and ionic species were investigated using both the all-atom optimized potential for liquid state, OPLS-AA, and the density functional (DFT) calculations. The energetic factors affecting the observed cluster distributions were examined. Calculations indicate that the large change in binding energy going from trimer to tetramer can be attributed more to pair-wise interactions than to cooperativity effects.Key words: alcohol clusters, cluster formation, DFT calculations, mass spectrometry, vacuum ultraviolet laser.
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39
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Shi YJ, Lo B, Tong L, Li X, Eustergerling BD, Sorensen TS. In situ diagnostics of the decomposition of silacyclobutane on a hot filament by vacuum ultraviolet laser ionization mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2007; 42:575-83. [PMID: 17285587 DOI: 10.1002/jms.1186] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
The gas-phase reaction products of silacyclobutane (SCB) and 1, 1-dideuterio-silacyclobutane (SCB-d(2)) from a hot-wire chemical vapor deposition (HWCVD) chamber were diagnosed in situ using vacuum ultraviolet (VUV) laser single-photon ionization (SPI) coupled with time-of-flight (TOF) mass spectrometry. The SCB molecule was found to decompose at a filament temperature as low as 900 degrees C. Both Si- (silylene, methylsilylene, and silene) and C-containing (ethene and propene) species were produced from the SCB decomposition on the filament. Ethene and propene were detected by the mass spectrometer. It is demonstrated that the formation of ethene is favored over that of propene. The experimental study of hot-wire decomposition of SCB-d(2) shows that propene is most likely produced by a process that is initiated by a 1,2-H(D) migration to form n-propylsilylene, followed by an equilibration with silacyclopropane, which then decomposes to propene. The detection of ethene in our experiment indicates that a competitive route of fragmentation exists for SCB decomposition on the filament. It has been shown that this competitive route occurs without H/D scrambling. The highly reactive silylene, silene, and methylsilylene species produced from SCB decomposition underwent either insertion reactions into the Si-H bonds of the parent molecule or pi-type addition reaction across the double and triple CC bonds. The dimerization product of silene, 1,3-disilacyclobutane, at m/z = 88 was also observed.
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Affiliation(s)
- Y J Shi
- Department of Chemistry, University of Calgary, Calgary, Alberta, T2N 1N4, Canada.
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40
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Mai FD, Lu HF, Li FY, Lin SH. Fragmentations of Hydroxymethyl Radical Cation: An Ab Initio Study. J CHIN CHEM SOC-TAIP 2007. [DOI: 10.1002/jccs.200700042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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41
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Tamenori Y, Okada K, Tabayashi K, Hiraya A, Gejo T, Honma K. Formation of H3O+ by the soft X-ray ionization of ethanol clusters. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2006.11.038] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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42
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Hu YJ, Fu HB, Bernstein ER. IR plus vacuum ultraviolet spectroscopy of neutral and ionic organic acid monomers and clusters: Propanoic acid. J Chem Phys 2006; 125:184309. [PMID: 17115754 DOI: 10.1063/1.2378628] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The vibrational spectrum of molecular propanoic acid, cooled in a supersonic expansion, in the region of 2500 to 7500 cm(-1) is obtained employing infrared plus vacuum ultraviolet nonresonant ionization detected spectroscopy. The fundamental and first overtone of the CH and OH stretch modes of cold propanoic acid molecules can be identified in the spectrum. Propanoic acid neutral and ionic clusters are also studied employing nonresonant ion dip and photodissociation spectroscopic techniques, respectively. For the neutral dimer, a sequence of features observed at ca. 2500-2700 cm(-1) can be assigned as combination bands of low frequency modes with the COH bending overtone; these features characterize the cyclic dimer ring structure. IR spectra of the larger neutral clusters n=3, 4, 5 indicate that they also have cyclic structures in which the OH groups are engaged in the cluster hydrogen bonding network. The CH groups are not involved in this hydrogen bonding structure. Free OH features are observed for the protonated ion clusters (C(2)H(5)COOH)(n)H(+), n=1,...,5, indicating that at least one OH group of these cluster ions is not involved in the cluster hydrogen bonding network. A comparison of the results for four hydrogen bonding neutral and ionic clusters (CH(3)OH, C(2)H(5)OH, CH(3)COOH, and C(2)H(5)COOH) is presented and discussed.
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Affiliation(s)
- Y J Hu
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
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Hu YJ, Fu HB, Bernstein ER. Infrared plus vacuum ultraviolet spectroscopy of neutral and ionic methanol monomers and clusters: New experimental results. J Chem Phys 2006; 125:154306. [PMID: 17059254 DOI: 10.1063/1.2357953] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
We present new observations of the infrared (IR) spectrum of neutral methanol and neutral and protonated methanol clusters employing IR plus vacuum ultraviolet (vuv) spectroscopic techniques. The tunable IR light covers the energy ranges of 2500-4500 cm(-1) and 5000-7500 cm(-1). The CH and OH fundamental stretch modes, the OH overtone mode, and combination bands are identified in the vibrational spectrum of supersonic expansion cooled methanol (2500-7500 cm(-1)). Cluster size selected IR plus vuv nonresonant infrared ion-dip infrared spectra of neutral methanol clusters, (CH(3)OH)(n) (n=2,[ellipsis (horizontal)],8), demonstrate that the methanol dimer has free and bonded OH stretch features, while clusters larger than the dimer display only hydrogen bonded OH stretch features. CH stretch mode spectra do not change with cluster size. These results suggest that all clusters larger than the dimer have a cyclic structure with OH groups involved in hydrogen bonding. CH groups are apparently not part of this cyclic binding network. Studies of protonated methanol cluster ions (CH(3)OH)(n)H(+) n=1,[ellipsis (horizontal)],7 are performed by size selected vuv plus IR photodissociation spectroscopy in the OH and CH stretch regions. Energies of the free and hydrogen bonded OH stretches exhibit blueshifts with increasing n, and these two modes converge to approximately 3670 and 3400 cm(-1) at cluster size n=7, respectively.
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Affiliation(s)
- Y J Hu
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
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Hu YJ, Fu HB, Bernstein ER. Infrared plus vacuum ultraviolet spectroscopy of neutral and ionic ethanol monomers and clusters. J Chem Phys 2006; 125:154305. [PMID: 17059253 DOI: 10.1063/1.2357952] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
A high sensitivity spectroscopy is employed to detect vibrational antiitions of ethanol neutrals and ions in a supersonic expansion. The infrared (IR) features located at 3682 and 3667 cm(-1) can be assigned to the OH stretch for the two neutral C(2)H(5)OH conformers, anti and gauche, respectively. Their overtone energies located at 7179 (anti) and 7141 (gauche) cm(-1) are also identified. The OH fundamental stretch for ethanol ions is redshifted around 210 cm(-1), while the CH stretch modes are unchanged for neutral and ionic C(2)H(5)OH at around 2900-3000 cm(-1). The charge on the ethanol ion is apparently localized on the oxygen atom. IR induced photodissociation spectroscopy is applied to the study of neutral and protonated ethanol clusters. Neutral and protonated ethanol cluster vibrations are observed. The CH modes are not perturbed by the clustering process. Neutral clusters display only hydrogen bonded OH features, while the protonated ionic clusters display both hydrogen bonded and non-hydrogen-bonded features. These spectroscopic results are analyzed to obtain qualitative structural information on neutral and ionic ethanol clusters.
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Affiliation(s)
- Y J Hu
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
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45
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Dong F, Heinbuch S, Rocca JJ, Bernstein ER. Dynamics and fragmentation of van der Waals clusters: (H2O)n, (CH3OH)n, and (NH3)n upon ionization by a 26.5eV soft x-ray laser. J Chem Phys 2006; 124:224319. [PMID: 16784286 DOI: 10.1063/1.2202314] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A tabletop soft x-ray laser is applied for the first time as a high energy photon source for chemical dynamics experiments in the study of water, methanol, and ammonia clusters through time of flight mass spectroscopy. The 26.5 eV/photon laser (pulse time duration of approximately 1 ns) is employed as a single photon ionization source for the detection of these clusters. Only a small fraction of the photon energy is deposited in the cluster for metastable dissociation of cluster ions, and most of it is removed by the ejected electron. Protonated water, methanol, and ammonia clusters dominate the cluster mass spectra. Unprotonated ammonia clusters are observed in the protonated cluster ion size range 2< or =n< or =22. The unimolecular dissociation rate constants for reactions involving loss of one neutral molecule are calculated to be (0.6-2.7)x10(4), (3.6-6.0)x10(3), and (0.8-2.0)x10(4) s(-1) for the protonated water (9< or =n< or =24), methanol (5< or =n< or =10), and ammonia (5< or =n< or =18) clusters, respectively. The temperatures of the neutral clusters are estimated to be between 40 and 200 K for water clusters (10< or =n< or =21), and 50-100 K for methanol clusters (6< or =n< or =10). Products with losses of up to five H atoms are observed in the mass spectrum of the neutral ammonia dimer. Large ammonia clusters (NH(3))(n) (n>3) do not lose more than three H atoms in the photoionization/photodissociation process. For all three cluster systems studied, single photon ionization with a 26.5 eV photon yields near threshold ionization. The temperature of these three cluster systems increases with increasing cluster size over the above-indicated ranges.
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Affiliation(s)
- F Dong
- NSF ERC for Extreme Ultraviolet Science and Technology and Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
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Deng JQ, Lipson RH. NMR study of hydrogen bonding in methanol carbon tetrachloride solutions. CAN J CHEM 2006. [DOI: 10.1139/v06-085] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The nuclear magnetic resonance (NMR) frequencies of the hydroxyl protons of methanol clusters in carbon tetrachloride were measured as a function of concentration between 245.4 and 320.2 K. The size of the methanol cluster (n) and the enthalpy and entropy of methanol self-association were obtained from nonlinear least-squares fittings to a model that assumed that only one dominant cluster was in equilibrium with the monomer at each temperature. The chemical shift measurements at 273 and 299.1 K fit best to theoretical curves calculated for a monomertetramer equilibrium. However, at higher and lower temperatures, the analyses indicate that the most dominant clusters are smaller and larger, respectively.Key words: alcohol liquid solutions, structure, hydrogen bonding, thermodynamics of self-association, nuclear magnetic resonance.
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Matsuda Y, Mori M, Hachiya M, Fujii A, Mikami N. Infrared spectroscopy of size-selected neutral clusters combined with vacuum-ultraviolet-photoionization mass spectrometry. Chem Phys Lett 2006. [DOI: 10.1016/j.cplett.2006.02.104] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Fu HB, Hu YJ, Bernstein ER. IR+vacuum ultraviolet (118 nm) nonresonant ionization spectroscopy of methanol monomers and clusters: Neutral cluster distribution and size-specific detection of the OH stretch vibrations. J Chem Phys 2006; 124:024302. [PMID: 16422578 DOI: 10.1063/1.2141951] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Small methanol clusters are formed by expanding a mixture of methanol vapor seeded in helium and are detected using vacuum UV (vuv) (118 nm) single-photon ionization/linear time-of-flight mass spectrometer (TOFMS). Protonated cluster ions, (CH3OH)(n-1)H+ (n=2-8), formed through intracluster ion-molecule reactions following ionization, essentially correlate to the neutral clusters, (CH3OH)n, in the present study using 118 nm light as the ionization source. Both experimental and Born-Haber calculational results clarify that not enough excess energy is released into protonated cluster ions to initiate further fragmentation in the time scale appropriate for linear TOFMS. Size-specific spectra for (CH3OH)n (n=4 to 8) clusters in the OH stretch fundamental region are recorded by IR+vuv (118 nm) nonresonant ion-dip spectroscopy through the detection chain of IR multiphoton predissociation and subsequent vuv single-photon ionization. The general structures and gross features of these cluster spectra are consistent with previous theoretical calculations. The lowest-energy peak contributed to each cluster spectrum is redshifted with increasing cluster size from n=4 to 8, and limits near approximately 3220 cm(-1) in the heptamer and octamer. Moreover, IR+vuv nonresonant ionization detected spectroscopy is employed to study the OH stretch first overtone of the methanol monomer. The rotational temperature of the clusters is estimated to be at least 50 K based on the simulation of the monomer rotational envelope under clustering conditions.
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Affiliation(s)
- H B Fu
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
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Shi YJ, Lipson RH. An overview of organic molecule soft ionization using vacuum ultraviolet laser radiation. CAN J CHEM 2005. [DOI: 10.1139/v05-193] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The utility of coherent vacuum ultraviolet (VUV) single-photon ionization (SPI) combined with time-of-flight mass spectrometry (TOF-MS) for organic molecule detection by parent mass is explored in this short review. Nonresonant tripling in phase-matched XeAr gas mixtures was used to generate photons at a fixed energy of 10.5 eV. Representative organic molecules with different functional groups were examined, including aliphatic and aromatic alkanes, alkenes, alkynes, alkanols, ethers, amines, aldehydes, ketones, carboxylic acids, and esters. In almost every case, the intensity of the resultant parent molecular ion peak detected by TOF-MS was found to be superior to that obtained using 70 eV electron impact (EI), and comparable to that obtained with 12 eV EI. In those instances when fragmentation reactions did occur, the resultant ions were similar to those found using EI but with significantly reduced mass spectral intensities. It was still possible to establish one dominant fragmentation pathway that could be used for molecular identification even if the parent molecular ion was not the strongest feature in the spectrum, for example, in the case of alcohols, alcohol clusters, and alcoholether adducts. Several of the fragment ions were metastably broadened. Not surprisingly, their known appearance energies or estimated reaction enthalpies were very similar to the fixed photon energy used. The success of using VUV for organic molecule soft ionization is attributed to the low photon energy that removes predominantly a π- or non-bonding electron from the functionalized species. As most organic compounds have ionization potentials in the 10.5 eV region, this approach is expected to be near universal.Key words: vacuum ultraviolet laser, single photon ionization, organic molecule detection, soft-ionization, mass spectrometry.
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Matsuda Y, Bernstein ER. On the Titanium Oxide Neutral Cluster Distribution in the Gas Phase: Detection through 118 nm Single-Photon and 193 nm Multiphoton Ionization. J Phys Chem A 2004; 109:314-9. [PMID: 16833349 DOI: 10.1021/jp040670h] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Titanium oxide clusters are generated in a supersonic expansion by laser ablation of the metal and reaction with oxygen (0.1-6%) in He expansion gas. Mass spectra of the titanium oxide clusters are observed by photoionization with lasers of three different wavelengths: 118, 193, and 355 nm. Only the 118 nm (10.5 eV) light can ionize Ti(m)O(n) neutral clusters without fragmentation. Both the 193 nm (6.4 eV) and 355 nm (3.5 eV) multiphoton ionization cause fragmentation of the neutral clusters during the ionization process and, thus, can complicate the determination of the stable neutral Ti(m)O(n) gas-phase species. Employing 118 nm single-photon ionization and line-width data, the Ti(m)O(2m) and Ti(m)O(2m+1) series are found to be the most stable neutral cluster species for high oxygen content in the expansion gas. Fragmentation during the multiphoton ionization process for 193 nm light yields the cluster ions Ti(m)O(2m-1,-2)+. These ions are formed by the loss of one or two oxygen atoms from Ti(m)O(2m,2m+1) neutral species. The dominant cluster growth process is suggested to be through the addition of TiO2 species. For low oxygen content (<2%) in the expansion gas, oxygen-deficient clusters of the form Ti(m)O(2m-1,-2) are also observed. These latter series are not fragmented by the 193 nm ionization process.
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Affiliation(s)
- Yoshiyuki Matsuda
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
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