1
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Hockey EK, McLane N, Vlahos K, McCaslin LM, Dodson LG. Matrix-formation dynamics dictate methyl nitrite conformer abundance. J Chem Phys 2024; 160:094303. [PMID: 38436440 DOI: 10.1063/5.0188433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 01/31/2024] [Indexed: 03/05/2024] Open
Abstract
Methyl nitrite has two stable conformational isomers resulting from rotation about the primary C-O-N-O dihedral angle: cis-CH3ONO and trans-CH3ONO, with cis being more stable by ∼5 kJ/mol. The barrier to rotational interconversion (∼45 kJ/mol) is too large for isomerization to occur under ambient conditions. This paper presents evidence of a change in conformer abundance when dilute CH3ONO is deposited onto a cold substrate; the relative population of the freshly deposited cis conformer is seen to increase compared to its gas-phase abundance, measured by in situ infrared spectroscopy. We observe abundance changes depending on the identity of the bath gas (N2, Ar, and Xe) and deposition angle. The observations indicate that the surface properties of the growing matrix influence conformer abundance-contrary to the widely held assumption that conformer abundance in matrices reflects gas-phase abundance. We posit that differences in the angle-dependent host-gas deposition dynamics affect the growing surfaces, causing changes in conformer abundances. Quantum chemistry calculations of the binding energies between CH3ONO and a single bath-gas component reveal that significant energetic stabilization is not observed in 1:1 complexes of N2:CH3ONO, Ar:CH3ONO, or Xe:CH3ONO. From our results, we conclude that the growing surface plays a significant role in trapping cis-CH3ONO more effectively than trans-CH3ONO, likely because cis-CH3ONO is more compact. Taken together, the observations highlight the necessity for careful characterization of conformers in matrix-isolated systems, emphasizing a need for further study into the deposition dynamics and surface structure of chemically inert matrices.
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Affiliation(s)
- Emily K Hockey
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
| | - Nathan McLane
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742, USA
| | - Korina Vlahos
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
| | | | - Leah G Dodson
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA
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2
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M Nunes C, Pereira NAM, Viegas LP, Pinho E Melo TMVD, Fausto R. Inducing molecular reactions by selective vibrational excitation of a remote antenna with near-infrared light. Chem Commun (Camb) 2021; 57:9570-9573. [PMID: 34546241 DOI: 10.1039/d1cc03574f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We demonstrate here that selective vibrational excitation of a moiety, remotely attached in relation to the molecular reaction site, might offer a generalized strategy for inducing bond-breaking/bond-forming reactions with exquisite precision. As a proof-of-principle, the electrocyclic ring-expansion of a benzazirine to a ketenimine was induced, in a cryogenic matrix, by near-IR light tuned at the overtone stretching frequency of its OH remote antenna. This accomplishment paves the way for harnessing IR vibrational excitation as a tool to guide a variety of molecular structure manipulations in an exceptional highly-selective manner.
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Affiliation(s)
- Cláudio M Nunes
- University of Coimbra, CQC, Department of Chemistry, 3004-535 Coimbra, Portugal.
| | - Nelson A M Pereira
- University of Coimbra, CQC, Department of Chemistry, 3004-535 Coimbra, Portugal.
| | - Luís P Viegas
- University of Coimbra, CQC, Department of Chemistry, 3004-535 Coimbra, Portugal.
| | | | - Rui Fausto
- University of Coimbra, CQC, Department of Chemistry, 3004-535 Coimbra, Portugal.
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3
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Qian W, Chu X, Song C, Wu Z, Jiao M, Liu H, Zou B, Rauhut G, Tew DP, Wang L, Zeng X. Hydrogen-Atom Tunneling in Metaphosphorous Acid. Chemistry 2020; 26:8205-8209. [PMID: 32302021 DOI: 10.1002/chem.202000844] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Indexed: 11/08/2022]
Abstract
Metaphosphorous acid (HOPO), a key intermediate in phosphorus chemistry, has been generated in syn- and anti-conformations in the gas phase by high-vacuum flash pyrolysis (HVFP) of a molecular precursor ethoxyphosphinidene oxide (EtOPO→C2 H4 +HOPO) at ca. 1000 K and subsequently trapped in an N2 -matrix at 2.8 K. Unlike the two conformers of the nitrogen analogue HONO, the anti-conformer of HOPO undergoes spontaneous rotamerization at 2.8 K via hydrogen-atom tunneling (HAT) with noticeable kinetic isotope effects for H/D (>104 for DOPO) and 16 O/18 O (1.19 for H18 OPO and 1.06 for HOP18 O) in N2 -matrices.
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Affiliation(s)
- Weiyu Qian
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, 215123, Suzhou, China
| | - Xianxu Chu
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, 215123, Suzhou, China
| | - Chao Song
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, 215123, Suzhou, China
| | - Zhuang Wu
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, 215123, Suzhou, China
| | - Mengqi Jiao
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, 215123, Suzhou, China
| | - Hanwen Liu
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, 215123, Suzhou, China
| | - Bin Zou
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, 215123, Suzhou, China
| | - Guntram Rauhut
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, Stuttgart, 70569, Germany
| | - David P Tew
- Max-Planck Institute for Solid State Research, Heisenbergstraße 1, Stuttgart, 70569, Germany
| | - Lina Wang
- Department of Chemistry, Fudan University, Shanghai, 200433, China
| | - Xiaoqing Zeng
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, 215123, Suzhou, China.,Department of Chemistry, Fudan University, Shanghai, 200433, China
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4
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Lopes Jesus A, Reva I, Nunes CM, Roque JP, Pinto SM, Fausto R. Kinetically unstable 2–isocyanophenol isolated in cryogenic matrices: Vibrational excitation, conformational changes and spontaneous tunneling. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2019.137069] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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5
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Nunes CM, Reva I, Fausto R. Conformational isomerizations triggered by vibrational excitation of second stretching overtones. Phys Chem Chem Phys 2019; 21:24993-25001. [PMID: 31710324 DOI: 10.1039/c9cp05070a] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Vibrational excitation using frequency-tunable IR laser light has been developed as a powerful tool for selective manipulation of molecular conformations. In this methodology, vibrational excitation has been typically applied to the first stretching overtones (∼80 kJ mol-1) but also to the fundamental modes (∼40 kJ mol-1). Here, we demonstrate that selective conformational isomerizations are also achieved using excitation to second stretching overtones (∼120 kJ mol-1). The extremely weak absorptions of the second stretching overtones of molecules isolated in low-temperature matrices were measured for the first time; here using three prototype molecules: hydroxyacetone (HA), glycolic acid (GAc) and glycolamide (GAm). Benchmarking of computed anharmonic IR spectra showed that the B3LYP/SNSD method provides the best agreement with experimental frequencies of the ν(OH), 2ν(OH) and 3ν(OH) modes for the studied molecules in argon matrices. Selective irradiation at the 3ν(OH) frequencies (9850-10 500 cm-1) of HA, GAc and GAm monomers in argon matrices at 15 K successfully triggers their conformational isomerization. These results open the door to extend control over conformations separated by higher barriers and to induce other transformations not energetically accessible by excitation to the fundamental or first stretching overtone modes.
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Affiliation(s)
- Cláudio M Nunes
- CQC, Department of Chemistry, University of Coimbra, 3004-535, Coimbra, Portugal.
| | - Igor Reva
- CQC, Department of Chemistry, University of Coimbra, 3004-535, Coimbra, Portugal.
| | - Rui Fausto
- CQC, Department of Chemistry, University of Coimbra, 3004-535, Coimbra, Portugal.
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6
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Lopes Jesus AJ, M. Nunes C, Fausto R, Reva I. Conformational control over an aldehyde fragment by selective vibrational excitation of interchangeable remote antennas. Chem Commun (Camb) 2018; 54:4778-4781. [DOI: 10.1039/c8cc01052h] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We apply vibrational antennas (OH or NH2 group) to achieve unprecedented conformational control over the heavy aldehyde fragment in 2-formyl-2H-azirine, using selective vibrational excitations of the OH or NH2 stretching overtones and combination modes.
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Affiliation(s)
| | | | - Rui Fausto
- CQC
- Department of Chemistry
- University of Coimbra
- Coimbra
- Portugal
| | - Igor Reva
- CQC
- Department of Chemistry
- University of Coimbra
- Coimbra
- Portugal
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7
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Duvernay F, Butscher T, Chiavassa T, Coussan S. IR induced photochemistry of glycolaldehyde in nitrogen matrix. Chem Phys 2017. [DOI: 10.1016/j.chemphys.2017.08.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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8
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Brown A, Pradhan E. Fitting potential energy surfaces to sum-of-products form with neural networks using exponential neurons. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2017. [DOI: 10.1142/s0219633617300014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In this paper, the use of the neural network (NN) method with exponential neurons for directly fitting ab initio data to generate potential energy surfaces (PESs) in sum-of-product form will be discussed. The utility of the approach will be highlighted using fits of CS2, HFCO, and HONO ground state PESs based upon high-level ab initio data. Using a generic interface between the neural network PES fitting, which is performed in MATLAB, and the Heidelberg multi-configuration time-dependent Hartree (MCTDH) software package, the PESs have been tested via comparison of vibrational energies to experimental measurements. The review demonstrates the potential of the PES fitting method, combined with MCTDH, to tackle high-dimensional quantum dynamics problems.
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Affiliation(s)
- Alex Brown
- Department of Chemistry, University of Alberta, Edmonton, AB, T6G 2G2, Canada
| | - E. Pradhan
- Department of Chemistry, University of Alberta, Edmonton, AB, T6G 2G2, Canada
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9
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Ryazantsev SV, Feldman VI, Khriachtchev L. Conformational Switching of HOCO Radical: Selective Vibrational Excitation and Hydrogen-Atom Tunneling. J Am Chem Soc 2017. [DOI: 10.1021/jacs.7b02605] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sergey V. Ryazantsev
- Department
of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
- Department
of Chemistry, University of Helsinki, P.O. Box 55, Helsinki FIN-00014, Finland
| | - Vladimir I. Feldman
- Department
of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Leonid Khriachtchev
- Department
of Chemistry, University of Helsinki, P.O. Box 55, Helsinki FIN-00014, Finland
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10
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Haupa KA, Tielens AGGM, Lee YP. Reaction of H + HONO in solid para-hydrogen: infrared spectrum of ˙ONH(OH). Phys Chem Chem Phys 2017; 19:16169-16177. [DOI: 10.1039/c7cp02621h] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hydrogenation reactions in the N/O chemical network are important for an understanding of the mechanism of formation of organic molecules in dark interstellar clouds, but many reactions remain unknown.
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Affiliation(s)
- Karolina Anna Haupa
- Department of Applied Chemistry and Institute of Molecular Science
- National Chiao Tung University
- Hsinchu 30010
- Taiwan
| | | | - Yuan-Pern Lee
- Department of Applied Chemistry and Institute of Molecular Science
- National Chiao Tung University
- Hsinchu 30010
- Taiwan
- Institute of Atomic and Molecular Sciences
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11
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Pradhan E, Brown A. A ground state potential energy surface for HONO based on a neural network with exponential fitting functions. Phys Chem Chem Phys 2017; 19:22272-22281. [DOI: 10.1039/c7cp04010e] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using CCSD(T)-F12/cc-pVTZ-F12 and CCSD(T)/CBS ab initio energies, two different six-dimensional ground state potential energy surfaces for HONO have been fit in sum-of-products form using neural network exponential fitting functions and tested by computing vibrational energies with MCTDH.
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Affiliation(s)
| | - Alex Brown
- Department of Chemistry
- University of Alberta
- Edmonton
- Canada
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12
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Bulychev VP, Buturlimova MV, Tokhadze KG. Anharmonic Calculation of the Structure, Vibrational Frequencies, and Intensities of the NH3···cis-HONO and NH3···cis-DONO Complexes. J Phys Chem A 2016; 120:6637-43. [PMID: 27472262 DOI: 10.1021/acs.jpca.6b05346] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The geometrical parameters, the frequencies, and absolute intensities for transitions between vibrational states of NH3···cis-HONO and NH3···cis-DONO hydrogen-bonded complexes are calculated using the approach earlier tested in calculations of isolated molecules of nitrous acid and the NH3···trans-HONO and NH3··trans-DONO complexes. Vibrational wave functions and energy values of the complexes are derived from variational solutions of anharmonic equations in one to four dimensions. The equilibrium nuclear configuration and potential energy surfaces are calculated by the MP2/aug-cc-pVTZ method with the basis set superposition error taken into account. Comparison of the obtained results with the analogous data calculated in the same approximation for isolated cis- and trans-HONO (DONO) molecules and the NH3···trans-HONO (DONO) complexes provides information about the changes in the spectroscopic and geometrical parameters of nitrous acid upon cis-trans transition, H/D substitution, and H-bond formation.
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Affiliation(s)
- V P Bulychev
- Department of Physics, St. Petersburg State University , 7/9 Universitetskaya Nab., St. Petersburg, 199034 Russian Federation
| | - M V Buturlimova
- Department of Physics, St. Petersburg State University , 7/9 Universitetskaya Nab., St. Petersburg, 199034 Russian Federation
| | - K G Tokhadze
- Department of Physics, St. Petersburg State University , 7/9 Universitetskaya Nab., St. Petersburg, 199034 Russian Federation
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13
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Oliveira AM, Lehman JH, McCoy AB, Lineberger WC. Photoelectron Spectroscopy of cis-Nitrous Acid Anion (cis-HONO(-)). J Phys Chem A 2016; 120:1652-60. [PMID: 26886478 DOI: 10.1021/acs.jpca.5b11797] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report photoelectron spectra of cis-HONO(-) formed from an association reaction of OH(-) and NO in a pulsed, plasma-entrainment ion source. The experimental data are assigned to the cis-HONO(-) isomer, which is predicted to be the global minimum on the anion potential energy surface. We do not find evidence for a significant contribution from trans-HONO(-). Electron photodetachment of cis-HONO(-) with 1613, 1064, 532, 355, and 301 nm photons accesses the ground X̃ (1)A' (S0) and excited ã (3)A″ (T1) states of neutral HONO. The photoelectron spectrum resulting from detachment forming cis-HONO (S0) exhibits a long vibrational progression, dominated by overtones and combination bands involving the central O-N stretching and ONO bending vibrations. This indicates that there is a significant change in the central O-N bond length between cis-HONO(-) and cis-HONO (S0). The electron affinity (EA) of cis-HONO is determined to be 0.356(8) eV. We also report the dissociation energy (D0) of cis-HONO(-), forming OH(-) + NO, as 0.594(9) eV, which is a factor of 4 decrease in the central O-N bond strength compared to neutral cis-HONO. The T1 state of cis-HONO is shown to be ∼2.3 eV higher in energy than cis-HONO (S0). Electron photodetachment to form cis-HONO (T1) accesses a transition state along the HO-NO bond dissociation coordinate. The resulting photoelectron spectrum exhibits broad peaks spaced by the terminal N═O stretching frequency. Electronic structure calculations and photoelectron spectrum simulations reported here show very good agreement with the experimental data.
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Affiliation(s)
- Allan M Oliveira
- JILA, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Julia H Lehman
- JILA, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
| | - Anne B McCoy
- Department of Chemistry, University of Washington , Seattle, Washington 98195, United States
| | - W Carl Lineberger
- JILA, and Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309, United States
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14
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Coussan S, Tarczay G. Infrared laser induced conformational and structural changes of glycine and glycine·water complex in low-temperature matrices. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2015.11.055] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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15
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Bulychev VP, Buturlimova MV, Tokhadze KG. Anharmonic Calculation of Structural and Spectroscopic Parameters of the cis-DONO Molecule. J Phys Chem A 2015; 119:9910-6. [DOI: 10.1021/acs.jpca.5b06466] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- V. P. Bulychev
- Physical
Faculty, St. Petersburg State University, Peterhof, St. Petersburg 198504, Russian Federation
| | - M. V. Buturlimova
- Physical
Faculty, St. Petersburg State University, Peterhof, St. Petersburg 198504, Russian Federation
| | - K. G. Tokhadze
- Physical
Faculty, St. Petersburg State University, Peterhof, St. Petersburg 198504, Russian Federation
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16
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Kuş N, Fausto R. Near-infrared and ultraviolet induced isomerization of crotonic acid in N2 and Xe cryomatrices: First observation of two high-energy trans C–O conformers and mechanistic insights. J Chem Phys 2014; 141:234310. [DOI: 10.1063/1.4903841] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Nihal Kuş
- CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
- Department of Physics, Anadolu University, 26470 Eskişehir, Turkey
| | - Rui Fausto
- CQC, Department of Chemistry, University of Coimbra, 3004-535 Coimbra, Portugal
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17
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Bulychev VP, Buturlimova MV, Tokhadze IK, Tokhadze KG. Calculation of structural and spectroscopic parameters of trans-DONO and the NH3···trans-DONO complex. Comparison with analogous parameters of trans-HONO and NH3···trans-HONO. J Phys Chem A 2014; 118:7139-45. [PMID: 25090019 DOI: 10.1021/jp505245x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The frequencies and absolute intensities for transitions between vibrational states of trans-DONO and NH3···trans-DONO are calculated using the approach earlier tested in calculations of trans-HONO and NH3···trans-HONO. The spectroscopic parameters were obtained in the harmonic approximation and from variational solutions of anharmonic Schrödinger equations in one to four dimensions with accurate potential energy and dipole moment surfaces. The calculated frequencies of trans-DONO are in good agreement with the experimental data. Our intensity values for trans-DONO and the frequencies and intensities for NH3···trans-DONO can be useful in interpretation of future experiments. Comparison of the transition frequencies and intensities and the averaged values of O-H (O-D) and N···O distances calculated for trans-DONO and its complex with ammonia with analogous parameters of trans-HONO and NH3···trans-HONO provides information about diverse isotope effects. For example, on H/D substitution the fundamental intensity for the ν2(N═O) mode of the lighter complex increases by a factor of 2.7, and the ν1 transition goes out of resonance with the 2ν3 overtone.
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Affiliation(s)
- Valentin P Bulychev
- Physical Faculty, St. Petersburg State University , Peterhof, St. Petersburg, 198504 Russian Federation
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18
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Pham P, Guo Y. A semiclassical study of cis-trans isomerization in HONO using an interpolating moving least-squares potential. J Chem Phys 2013; 138:144304. [DOI: 10.1063/1.4799270] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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Cao Q, Melavuori M, Lundell J, Räsänen M, Khriachtchev L. Matrix-isolation and ab initio study of the complex between formic acid and xenon. J Mol Struct 2012. [DOI: 10.1016/j.molstruc.2012.05.027] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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20
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Kuş N, Sharma A, Reva I, Lapinski L, Fausto R. Using heavy atom rare gas matrix to control the reactivity of 4-methoxybenzaldehyde: A comparison with benzaldehyde. J Chem Phys 2012; 136:144509. [DOI: 10.1063/1.3701734] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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21
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Sala M, Gatti F, Lauvergnat D, Meyer HD. Effect of the overall rotation on the cis–trans isomerization of HONO induced by an external field. Phys Chem Chem Phys 2012; 14:3791-801. [DOI: 10.1039/c2cp23709a] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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22
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Raff JD, Szanyi J, Finlayson-Pitts BJ. Thermal and photochemical oxidation of self-assembled monolayers on alumina particles exposed to nitrogen dioxide. Phys Chem Chem Phys 2011; 13:604-11. [DOI: 10.1039/c0cp01041c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Trakhtenberg LI, Fokeyev AA, Zyubin AS, Mebel AM, Lin SH. Effect of the Medium on Intramolecular H-Atom Tunneling: Cis−Trans Conversion of Formic Acid in Solid Matrixes of Noble Gases. J Phys Chem B 2010; 114:17102-12. [DOI: 10.1021/jp1073472] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Leonid I. Trakhtenberg
- Semenov Institute of Chemical Physics, Russian Academy of Sciences, 4, Kosygina Str., Moscow 119991, Russia, SSC RF “Karpov Institute of Physical Chemistry”, 10, Vorontsovo Pole Str., Moscow 105064, Russia, Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia, Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States, and Department of Applied Chemistry and Institute of Molecular Sciences,
| | - Anatoly A. Fokeyev
- Semenov Institute of Chemical Physics, Russian Academy of Sciences, 4, Kosygina Str., Moscow 119991, Russia, SSC RF “Karpov Institute of Physical Chemistry”, 10, Vorontsovo Pole Str., Moscow 105064, Russia, Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia, Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States, and Department of Applied Chemistry and Institute of Molecular Sciences,
| | - Alexander S. Zyubin
- Semenov Institute of Chemical Physics, Russian Academy of Sciences, 4, Kosygina Str., Moscow 119991, Russia, SSC RF “Karpov Institute of Physical Chemistry”, 10, Vorontsovo Pole Str., Moscow 105064, Russia, Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia, Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States, and Department of Applied Chemistry and Institute of Molecular Sciences,
| | - Alexander M. Mebel
- Semenov Institute of Chemical Physics, Russian Academy of Sciences, 4, Kosygina Str., Moscow 119991, Russia, SSC RF “Karpov Institute of Physical Chemistry”, 10, Vorontsovo Pole Str., Moscow 105064, Russia, Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia, Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States, and Department of Applied Chemistry and Institute of Molecular Sciences,
| | - S. H. Lin
- Semenov Institute of Chemical Physics, Russian Academy of Sciences, 4, Kosygina Str., Moscow 119991, Russia, SSC RF “Karpov Institute of Physical Chemistry”, 10, Vorontsovo Pole Str., Moscow 105064, Russia, Institute of Problems of Chemical Physics, Russian Academy of Sciences, Chernogolovka, Moscow Region 142432, Russia, Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States, and Department of Applied Chemistry and Institute of Molecular Sciences,
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24
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Maçôas EMS, Khriachtchev L, Pettersson M, Fausto R, Räsänen M. Rotational isomerization of small carboxylic acids isolated in argon matrices: tunnelling and quantum yields for the photoinduced processes. Phys Chem Chem Phys 2009; 7:743-9. [PMID: 19791357 DOI: 10.1039/b416641h] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The quantum yields for internal rotation around the C-O bond induced by excitation of the first overtone of the hydroxyl stretching mode in formic, acetic, and propionic acids isolated in solid Ar are comparatively discussed. The tunnelling kinetics for isomerization from the higher energy arrangement of the carboxylic group (cis) to the lower energy arrangement (trans) in this series of compounds is also analysed. Finally, the quantum yield for the C(alpha)-C isomerization in propionic acid was investigated and, in contrast with the C-O isomerization, shown to be probably sensitive to the local matrix morphology.
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Affiliation(s)
- Ermelinda M S Maçôas
- Laboratory of Physical Chemistry, University of Helsinki, PO Box 55, FIN-00014 Helsinki, Finland
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Botan V, Hamm P. Intramolecular vibrational energy relaxation in nitrous acid (HONO). J Chem Phys 2008; 129:164506. [DOI: 10.1063/1.2996355] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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26
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Botan V, Hamm P. Temperature dependence of the IR drivencis-transisomerization of nitrous acid (HONO). J Chem Phys 2008; 129:114510. [DOI: 10.1063/1.2978386] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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27
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Botan V, Hamm P. Rotational dynamics of nitrous acid (HONO) in Kr matrix. J Chem Phys 2008; 129:044507. [DOI: 10.1063/1.2956503] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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28
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Le HM, Raff LM. Cis→trans, trans→cis isomerizations and N–O bond dissociation of nitrous acid (HONO) on an ab initio potential surface obtained by novelty sampling and feed-forward neural network fitting. J Chem Phys 2008; 128:194310. [DOI: 10.1063/1.2918503] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [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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Khriachtchev L. Rotational isomers of small molecules in noble-gas solids: From monomers to hydrogen-bonded complexes. J Mol Struct 2008. [DOI: 10.1016/j.molstruc.2007.10.011] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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30
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Hamm P. The infrared-driven cis–trans isomerization of nitrous acid HONO III: A mixed quantum–classical simulation. Chem Phys 2008. [DOI: 10.1016/j.chemphys.2007.10.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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31
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Richter F, Gatti F, Léonard C, Le Quéré F, Meyer HD. Time-dependent wave packet study ontrans-cisisomerization of HONO driven by an external field. J Chem Phys 2007; 127:164315. [DOI: 10.1063/1.2784553] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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32
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Miller Y, Chaban GM, Finlayson-Pitts BJ, Gerber RB. Photochemical processes induced by vibrational overtone excitations: dynamics simulations for cis-HONO, trans-HONO, HNO3, and HNO3-H2O. J Phys Chem A 2007; 110:5342-54. [PMID: 16623461 DOI: 10.1021/jp0559940] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Photochemical processes in HNO3, HNO3-H2O, and cis- and trans-HONO following overtone excitation of the OH stretching mode are studied by classical trajectory simulations. Initial conditions for the trajectories are sampled according to the initially prepared vibrational wave function. Semiempirical potential energy surfaces are used in "on-the-fly" simulations. Several tests indicate at least semiquantitative validity of the potential surfaces employed. A number of interesting new processes and intermediate species are found. The main results include the following: (1) In excitation of HNO3 to the fifth and sixth OH-stretch overtone, hopping of the H atom between the oxygen atoms is found to take place in nearly all trajectories, and can persist for many picoseconds. H-atom hopping events have a higher yield and a faster time scale than the photodissociation of HNO3 into OH and NO2. (2) A fraction of the trajectories for HNO3 show isomerization into HOONO, which in a few cases dissociates into HOO and NO. (3) For high overtone excitation of HONO, isomerization into the weakly bound species HOON is seen in all trajectories, in part of the events as an intermediate step on the way to dissociation into OH + NO. This process has not been reported previously. Well-established processes for HONO, including cis-trans isomerization and H hopping are also observed. (4) Only low overtone levels of HNO3-H2O have sufficiently long liftimes to be spectrocopically relevant. Excitation of these OH stretching overtones is found to result in the dissociation of the cluster H hopping, or dissociation of HNO3 does not take place. The results demonstrate the richness of processes induced by overtone excitation of HNO(x) species, with evidence for new phenomena. Possible relevance of the results to atmospheric processes is discussed.
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Affiliation(s)
- Y Miller
- Department of Physical Chemistry and Fritz Haber Research Center, The Hebrew University, Jerusalem 91904, Israel
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33
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Marushkevich K, Khriachtchev L, Räsänen M. High-energy conformer of formic acid in solid neon: Giant difference between the proton tunneling rates ofcismonomer andtrans-cisdimer. J Chem Phys 2007; 126:241102. [PMID: 17614528 DOI: 10.1063/1.2752152] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
We study the conformational reorganization of formic acid (FA) in solid neon and report the higher-energy cis-FA monomer and one form of the trans-cis FA dimers. They were prepared by selective vibrational excitation of the trans-FA monomer and trans-trans dimer. The proton tunneling decay of cis-FA monomer is surprisingly very fast in solid neon, two orders of magnitude faster than in solid argon. It was also found that the stability of the trans-cis dimer against proton tunneling is enormously enhanced in solid neon compared to the monomer (by a factor of approximately 300). These results are discussed in terms of matrix solvation and hydrogen bonding.
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Affiliation(s)
- Kseniya Marushkevich
- Laboratory of Physical Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland
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34
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Marushkevich K, Khriachtchev L, Räsänen M. High-energy conformer of formic acid in solid hydrogen: conformational change promoted by host excitation. Phys Chem Chem Phys 2007; 9:5748-51. [DOI: 10.1039/b712647f] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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35
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Isoniemi E, Khriachtchev L, Makkonen M, Räsänen M. UV Photolysis Products of Propiolic Acid in Noble-Gas Solids. J Phys Chem A 2006; 110:11479-87. [PMID: 17020260 DOI: 10.1021/jp062080k] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Photolysis (193 nm) of propiolic acid (HCCCOOH) was studied with Fourier transform infrared spectroscopy in noble-gas (Ar, Kr, and Xe) solid matrixes. The photolysis products were assigned using ab initio quantum chemistry calculations. The novel higher-energy conformer of propiolic acid was efficiently formed upon UV irradiation, and it decayed back to the ground-state conformer on a time scale of approximately 10 min by tunneling of the hydrogen atom through the torsional energy barrier. In addition, the photolysis produced a number of matrix-isolated 1:1 molecular complexes such as HCCH...CO2, HCCOH...CO, and H2O...C3O. The HCCH...CO2 complex dominated among the photolysis products, and the computations suggested a parallel geometry of this complex characterized by an interaction energy of -9.6 kJ/mol. The HCCOH...CO complex also formed efficiently, but its concentration was strongly limited by its light-induced decomposition. In this complex, the most probable geometry was found to feature the interaction of carbon monoxide with the OH group via the carbon atom, and the computational interaction energy was determined to be -18.3 kJ/mol. The formation of the strong H2O...C3O complex (interaction energy -21 kJ/mol) was less efficient, which might be due to the inefficiency of the involved radical reaction.
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Affiliation(s)
- Esa Isoniemi
- Laboratory of Physical Chemistry, P.O. Box 5, University of Helsinki, Helsinki FIN-00014, Finland
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36
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Botan V, Schanz R, Hamm P. The infrared-driven cis-trans isomerization of HONO. II: Vibrational relaxation and slow isomerization channel. J Chem Phys 2006; 124:234511. [PMID: 16821933 DOI: 10.1063/1.2204914] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In a recent paper [R. Schanz et al., J. Chem. Phys. 122, 044509 (2005)], we investigated the IR-driven cis-trans isomerization of HONO in a Kr matrix with the help of femtosecond IR spectroscopy. We found that isomerization occurs on a 20 ps time scale, however, with a cis-->trans quantum yield of only 10% that is significantly below the value reported in the literature (close to 100%). At the same time, we concluded that vibrational energy has not completely dissipated out of the molecule at the maximum delay time we reached in this study (500 ps). In order to verify whether additional, slower reaction channels exist, we extend the study here to delay times up to 100 ns. At a temperature of 32 K, we indeed find an additional isomerization channel on a 2 ns timescale, which increases the total cis-->trans quantum yield to approximately 30%. The trans-->cis quantum yield is approximately 7%. There is still a discrepancy between the quantum yields we observe and the literature values, however, we provide experimental evidence that this discrepancy is due to the different temperatures of our study. Vibrational cooling occurs on a 20 ns time scale, and cascades in a highly nonstatistical manner through one single normal mode (most likely the ONO bending mode nu(5)). Intermolecular energy dissipation into the rare gas matrix is more efficient than intramolecular vibrational energy redistribution and the matrix environment can certainly not be considered a weak perturbation.
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Affiliation(s)
- Virgiliu Botan
- Physikalisch-Chemisches Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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37
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Ahokas JME, Vaskonen KJ, Kunttu HM. Structure and Matrix Isolation Infrared Spectrum of Formyl Fluoride Dimer: Blue-Shift of the C−H Stretching Frequency. J Phys Chem A 2006; 110:7816-21. [PMID: 16789767 DOI: 10.1021/jp061188x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Infrared spectroscopy (IR) of formyl fluoride (HCOF) dimer is studied in low-temperature argon and krypton matrixes. New IR absorptions, ca. 17 cm(-1) blue shifted from the monomer C-H stretching fundamental, are assigned to the HCOF dimer. The MP2/6-311++G calculations were utilized to define structures and harmonic frequencies of various HCOF dimers. Among the four optimized structures, the dimer having two C-H...O hydrogen bonds possesses strongest intermolecular bonding. The calculated harmonic frequencies of this dimer structure are shifted from the monomer similarly as observed in the experiment. Thus, we suggest that the experimentally observed blue shifted C-H bands belong to the dimer with two C-H...O hydrogen bonds. This observation includes the HCOF dimer to the class of hydrogen bonded complexes showing blue shift in their vibrational energies.
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Affiliation(s)
- Jussi M E Ahokas
- Nanoscience Center, Department of Chemistry, University of Jyväskylä, Finland
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38
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Pasin G, Gatti F, Iung C, Meyer HD. Theoretical investigation of intramolecular vibrational energy redistribution in highly excited HFCO. J Chem Phys 2006; 124:194304. [PMID: 16729811 DOI: 10.1063/1.2192499] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The present paper is devoted to the simulations of the intramolecular vibrational energy redistribution (IVR) in HFCO initiated by an excitation of the out-of-plane bending vibration [nnu(6)=2,4,6,...,18,20]. Using a full six-dimensional ab initio potential energy, the multiconfiguration time-dependent Hartree (MCTDH) method was exploited to propagate the corresponding six-dimensional wave packets. This study emphasizes the stability of highly excited states of the out-of-plane bending mode which exist even above the dissociation threshold. More strikingly, the structure of the IVR during the first step of the dynamics is very stable for initial excitations ranging from 2nu(6) to 20nu(6). This latter result is consistent with the analysis of the eigenstates obtained, up to 10nu(6), with the aid of the Davidson algorithm in a foregoing paper [Iung and Ribeiro, J. Chem. Phys. 121, 174105 (2005)]. The present study can be considered as complementary to this previous investigation. This paper also shows how MCTDH can be used to predict the dynamical behavior of a strongly excited system and to determine the energies of the corresponding highly excited states.
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Affiliation(s)
- Gauthier Pasin
- LSDSMS (UMR 5636-CNRS), CC 014, Université Montpellier II, F-34095 Montpellier Cedex 05, France.
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39
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Schanz R, Boţan V, Hamm P. A femtosecond study of the infrared-driven cis-trans isomerization of nitrous acid (HONO). J Chem Phys 2006; 122:44509. [PMID: 15740269 DOI: 10.1063/1.1834567] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We investigate the dynamics and mechanism of the IR-driven cis-trans isomerization of nitrous acid (HONO) in a low-temperature krypton matrix applying ultrafast time resolved IR spectroscopy. After excitation of the OH-stretching mode the trans HONO state decays biexponentially on a 8 and 260 ps time scale. The initially excited cis HONO state decays on a 20 ps time scale. Cis HONO isomerizes with 10% quantum yield on a 20 ps time scale to trans HONO. The quantum yield we observe is significantly smaller than the previously reported 100%, which could imply that additional, much slower reaction channels exist. We furthermore developed a four-dimensional model of the system, which includes the three proton intramolecular degrees of freedom of HONO fully quantum mechanically and one intermolecular translational degree of freedom of the molecule in the crystal cage. We find that cis-trans isomerization necessarily is accompanied by a translation of the molecule as a whole in the crystal cage. The translational degree of freedom tunes the intramolecular proton states of HONO with respect to each other. When resonances occur, the proton states might couple and transfer population. We suggest a possible reaction pathway, where the cis OH-stretch excited state first couples to a high cis torsional mode, which then may transfer almost instantaneously to the trans side. The model qualitatively explains all experimental observations.
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Affiliation(s)
- Roland Schanz
- Physikalisch-Chemisches Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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40
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41
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Maçôas EMS, Khriachtchev L, Pettersson M, Fausto R, Räsänen M. Internal Rotation in Propionic Acid: Near-Infrared-Induced Isomerization in Solid Argon. J Phys Chem A 2005; 109:3617-25. [PMID: 16839027 DOI: 10.1021/jp044070u] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The conformational system of propionic acid (CH3CH2COOH) is studied in solid argon. It is predicted by the ab initio calculations that this molecule has four stable conformers. These four structures are denoted Tt, Tg+/-, Ct, and Cg+/-, and they differ by the arrangement around the C-O and Calpha-C bonds. The ground-state Tt conformer is the only form present at 8 K after deposition of an argon matrix containing propionic acid. For the CH3CH2COOH and CH3CH2COOD isotopologues, narrow-band excitation of the first hydroxyl stretching overtone of the conformational ground state promotes the Calpha-C and C-O internal rotations producing the Tg+/- and Ct conformers, respectively. A subsequent vibrational excitation of the produced Tg+/- form induces its conversion to the Cg+/- conformer by rotation around the C-O bond. In the dark, all of the produced conformers decay to the conformational ground state at different rates. The decay kinetics and its temperature dependence allow the identification of the conformers by IR absorption spectroscopy, which is supported by ab initio calculations of their vibrational spectra. For the CH3CH2COOD isotopologue, the excitation of molecules isolated in different matrix sites results in site-dependent photoisomerization rates for the Calpha-C and C-O internal rotations, which also confirm the identification of the photoproducts.
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Affiliation(s)
- Ermelinda M S Maçôas
- Laboratory of Physical Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland.
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42
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Bulychev V, Tokhadze K. Multidimensional anharmonic calculation of the vibrational frequencies and intensities for the trans and cis isomers of HONO with the use of normal coordinates. J Mol Struct 2004. [DOI: 10.1016/j.molstruc.2004.01.072] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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43
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Luckhaus D. Multi-arrangement quantum dynamics in 6D: cis–trans isomerization and 1,3-hydrogen transfer in HONO. Chem Phys 2004. [DOI: 10.1016/j.chemphys.2004.06.038] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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44
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Macoas EMS, Khriachtchev L, Pettersson M, Fausto R, Rasanen M. Rotational isomerism of acetic acid isolated in rare-gas matrices: Effect of medium and isotopic substitution on IR-induced isomerization quantum yield and cis→trans tunneling rate. J Chem Phys 2004; 121:1331-8. [PMID: 15260676 DOI: 10.1063/1.1760733] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Rotational isomerization of acetic acid (CH3COOH) is studied in Ar, Kr, and Xe matrices. The light-induced trans-->cis reaction is promoted using resonant excitation of a number of modes in the 3500-7000 cm(-1) region, and the quantum yields for this process are measured for various acetic acid isotopologues and matrix materials. For excitation of acetic acid at energies above the predicted isomerization energy barrier (> or =4400 cm(-1)), the measured quantum yields are in average 2%-3%, and this is one order of magnitude smaller than the corresponding values known for formic acid (HCOOH). This difference is interpreted in terms of the presence of the methyl group in acetic acid, which enhances energy relaxation channels competing with the rotational isomerization. This picture is supported by the observed large effect of deuteration of the methyl group on the photoisomerization quantum yield. The trans-->cis reaction quantum yields are found to be similar for Ar, Kr, and Xe matrices, suggesting similar energy relaxation processes for this molecule in the various matrices. The IR-induced cis-->trans process, studied for acetic acid deuterated in the hydroxyl group, shows reliably larger quantum yields as compared with the trans-->cis process. For pumping of acetic acid at energies below the predicted isomerization barrier, the trans-->cis reaction quantum yields decrease strongly when the photon energy decreases, and tunneling is the most probable mechanism for this process. For the cis-->trans dark reaction, the observed temperature and medium effects indicate the participation of the lattice phonons in the tunneling-induced process.
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Affiliation(s)
- E M S Macoas
- Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland.
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45
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Richter F, Rosmus P, Gatti F, Meyer HD. Time-dependent wave packet study on trans-cis isomerization of HONO. J Chem Phys 2004; 120:6072-84. [PMID: 15267491 DOI: 10.1063/1.1651051] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Using a full six-dimensional ab initio potential energy surface and nuclear motion Hamiltonian, time-dependent computations were performed for the cis-trans isomerization of HONO. The multiconfiguration time-dependent Hartree method was used to propagate the six-dimensional wave packets. The initial excitations were chosen to be excitations of the local stretch modes and the HON local bend mode. The energy redistribution within 2 to 5 ps in the energy region of the OH stretching modes in both isomers was analyzed. The Fourier transformed frequency domain spectra were attributed to the eigenstates calculated previously by the time-independent variational approach. The results are also compared with classical trajectory computations of Thomson et al. on empirical surfaces. In agreement with matrix experiments, the cis-->trans isomerization was found to be much faster than the opposite interconversion. The intramolecular dynamics were found to be very complex involving numerous weakly excited delocalized eigenstates and anharmonic resonances. Particularly in the cis-isomer, the excitation of the HON bending local mode leads to fast energy redistribution in cis-trans delocalized modes. Neither the excitation of the OH stretching local mode in the cis nor in the trans form produces a fast isomerization, in agreement with the strongly localized characters of the corresponding eigenstates calculated variationally by Richter et al. and the gas phase spectra of HONO.
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Affiliation(s)
- Falk Richter
- Laboratoire de Chimie Theorique, Universite de Marne la Vallee, F-77454-Champs sur Marne, France
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46
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Maçôas EMS, Khriachtchev L, Fausto R, Räsänen M. Photochemistry and Vibrational Spectroscopy of the Trans and Cis Conformers of Acetic Acid in Solid Ar. J Phys Chem A 2004. [DOI: 10.1021/jp037840v] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- E. M. S. Maçôas
- Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland, and Department of Chemistry (CQC), University of Coimbra, P-3004-535 Coimbra, Portugal
| | - L. Khriachtchev
- Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland, and Department of Chemistry (CQC), University of Coimbra, P-3004-535 Coimbra, Portugal
| | - R. Fausto
- Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland, and Department of Chemistry (CQC), University of Coimbra, P-3004-535 Coimbra, Portugal
| | - M. Räsänen
- Department of Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki, Finland, and Department of Chemistry (CQC), University of Coimbra, P-3004-535 Coimbra, Portugal
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47
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Richter F, Hochlaf M, Rosmus P, Gatti F, Meyer HD. A study of the mode-selective trans–cis isomerization in HONO using ab initio methodology. J Chem Phys 2004; 120:1306-17. [PMID: 15268256 DOI: 10.1063/1.1632471] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Ab initio calculations on the six-dimensional cis--trans double minimum potential energy surface of the electronic ground state of the HONO molecule were performed using a coupled cluster approach. An analytic fit to the data points was established. The interconversion barrier was calculated to be 4105 cm(-1). The nuclear motion problem was solved variationally using a full six-dimensional Hamiltonian in internal coordinates. The eigenstates up to about 3650 cm(-1) were tentatively assigned by harmonic quantum numbers. The assignment was based on the mean values of the internal coordinates of the six-dimensional eigenfunctions and on a comparison of the eigenenergies with those calculated by second-order perturbation theory from a full quartic force field in dimensionless normal coordinates. In cold matrices the trans- and the cis-OH nu(1) stretching modes and the first trans- and cis-NO 2nu(2) stretching overtones lead to isomerization. In the isolated molecule these modes (J=0) were found to be entirely localized. However, several overtones of the nu(4) ONO bending and nu(5) N-O stretching, which are close in energy to the OH stretch and combined with the torsional mode, were found to be strongly cis-trans delocalized.
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Affiliation(s)
- Falk Richter
- Laboratoire de Chimie Theorique, Universite de Marne la Vallee, F 77454-Champs sur Marne, France
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48
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Maçôas EMS, Khriachtchev L, Pettersson M, Juselius J, Fausto R, Räsänen M. Reactive vibrational excitation spectroscopy of formic acid in solid argon: Quantum yield for infrared inducedtrans→cisisomerization and solid state effects on the vibrational spectrum. J Chem Phys 2003. [DOI: 10.1063/1.1624598] [Citation(s) in RCA: 48] [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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49
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Maçôas EMS, Khriachtchev L, Pettersson M, Fausto R, Räsänen M. Rotational Isomerism in Acetic Acid: The First Experimental Observation of the High-Energy Conformer. J Am Chem Soc 2003; 125:16188-9. [PMID: 14692750 DOI: 10.1021/ja038341a] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The high-energy conformer of acetic acid (cis-AA) is produced in an Ar matrix by vibrational excitation of the OH stretching overtone of the ground conformational state (trans-AA). IR-absorption spectroscopy provides a clear identification of the reaction product. cis-AA converts back to trans-AA in a time scale of minutes at 8 K by tunneling.
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Affiliation(s)
- Ermelinda M S Maçôas
- Laboratory of Physical Chemistry, P.O. Box 55, FIN-00014 University of Helsinki, Finland
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50
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Guo Y, Thompson DL. A theoretical study ofcis–transisomerization in HONO using an empirical valence bond potential. J Chem Phys 2003. [DOI: 10.1063/1.1530585] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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