1
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Aardema MN, McBane GC, North SW. Ozone Photodissociation in the Singlet Channel at 226 nm. J Phys Chem A 2022; 126:6898-6907. [PMID: 36129835 DOI: 10.1021/acs.jpca.2c04832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the rotational state distribution and vector correlations of the O2(a 1Δg, v = 0) fragments arising from the 226 nm photodissociation of jet-cooled O3. Consistent with previously reported trends, the rotational distribution is shifted to higher rotational states with decreasing wavelength. We observe highly suppressed odd rotational state populations due to a strong Λ-doublet propensity. The measured rotational distribution is in agreement with classical trajectory calculations for the v = 0 products, although the distribution is slightly narrower than predicted. The spatial anisotropy follows the previously observed trend of decreasing β with increasing photon energy with β = 0.72 ± 0.14 for v = 0, j = 38. As expected for a triatomic molecule, the v-j correlation is consistent with v perpendicular to j, but the measured correlation is nonlimiting due, in part, to rotational and translational depolarization. The j-dependent line width of the O2(a 1Δg) REMPI spectrum is also discussed in connection with the lifetime of the resonant O2(d 1Πg) state due to predissociation via the II 1Πg valence state.
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Affiliation(s)
- Megan N Aardema
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
| | - George C McBane
- Department of Chemistry, Grand Valley State University, Allendale, Michigan 49401, United States
| | - Simon W North
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, United States
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2
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Parsons BF, Rivera MR, Onder MK. NO (A) Rotational State Distributions from Photodissociation of the N 2-NO Complex. J Phys Chem A 2022; 126:5729-5737. [PMID: 35994689 DOI: 10.1021/acs.jpca.2c04265] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have recorded the resonance-enhanced multiphoton ionization spectrum for NO (A) products from photodissociation of the N2-NO complex. We made measurements at excitation energies ranging from 28 to 758 cm-1 above the threshold to produce NO (A) + N2 (X) products, and the resulting spectra reveal the NO (A) rotational states formed during dissociation, allowing us to determine the rotational state distribution. At the lowest available energies, 28 and 50 cm-1 above threshold, we observed contributions from NO (A) rotational states that exceed the available energy and must originate from excitation due to hotbands of the complex. At all higher energies, we did not observe any energetically disallowed NO (A) rotational states, and for all available energies above 259 cm-1 the observed rotational transitions do not extend to the maximum allowed by energy conservation. Furthermore, the observed distributions were typically biased toward low rotational states, in contrast with expectations from vibrational predissociation. From the rotational state distributions, we determined the average fraction of energy partitioned into NO (A) rotation, fNO rot, ave, to be 0.088 at the highest available energy, and this fraction increased as the available energy decreased. By combining the average NO (A) rotational energy along with the average center-of-mass translational energy from our previous work, we determined the average rotational energy for the undetected N2 (X) photoproduct. The results showed that the N2 fragment has a higher average rotational energy relative to the NO fragment. Finally, we found that the NO (A) rotational state distribution was colder than expected for a statistical dissociation.
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Affiliation(s)
- Bradley F Parsons
- Department of Chemistry and Biochemistry, Creighton University, 2500 California Plaza, Omaha, Nebraska 68178, United States
| | - Marcos R Rivera
- Department of Chemistry and Biochemistry, Creighton University, 2500 California Plaza, Omaha, Nebraska 68178, United States
| | - Michael K Onder
- Department of Chemistry and Biochemistry, Creighton University, 2500 California Plaza, Omaha, Nebraska 68178, United States
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3
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Parsons BF, Draney AW, Warder HJ, Rivera MR, Onder MK. Anisotropy Measurements from the Near-Threshold Photodissociation of the N 2-NO Complex. J Phys Chem A 2022; 126:1386-1392. [PMID: 35179379 DOI: 10.1021/acs.jpca.1c10514] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have used velocity map ion imaging to measure the angular anisotropy of the NO (A) products from the photodissociation of the N2-NO complex. Our experiment ranged from 108 to 758 cm-1 above the threshold energy to form NO (A) + N2 (X) products, and these measurements reveal, for the first time, a strong angular anisotropy from photodissociation. At 108 cm-1 above the photodissociation threshold, we observed NO (A) photoproducts recoil preferentially perpendicular to the laser polarization axis with an average anisotropy parameter, β = -0.25; however, as the available energy was increased, the anisotropy increased, and at 758 cm-1 above the threshold energy, we found an average β = +0.28. The observed changes in the angular anisotropy of the NO (A) photoproduct are qualitatively similar to those observed for the photodissociation of the Ar-NO complex and likely result from changes in the region of the excited state potential energy surface accessed during the electronic excitation. At the lowest available energy, we also noted a large contribution from hotband excitation; however, this contribution decreased as the available energy increased. The outsized contribution at the lowest available energy may result from hotbands having better Franck-Condon overlap with the excited electronic state near threshold. Finally, we contrast the experimental center of mass translational energy distribution with a statistical energy distribution determined from phase space theory. The experimental and statistical distributions show pronounced disagreement, particularly at low kinetic energies, with the experimental one showing less dissociation resulting in high rotational levels of the fragments.
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Affiliation(s)
- Bradley F Parsons
- Department of Chemistry and Biochemistry, Creighton University, 2500 California Plaza, Omaha, Nebraska 68178, United States
| | - Adrian W Draney
- Department of Chemistry and Biochemistry, Creighton University, 2500 California Plaza, Omaha, Nebraska 68178, United States
| | - Hunter J Warder
- Department of Chemistry and Biochemistry, Creighton University, 2500 California Plaza, Omaha, Nebraska 68178, United States
| | - Marcos R Rivera
- Department of Chemistry and Biochemistry, Creighton University, 2500 California Plaza, Omaha, Nebraska 68178, United States
| | - Michael K Onder
- Department of Chemistry and Biochemistry, Creighton University, 2500 California Plaza, Omaha, Nebraska 68178, United States
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4
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Cho HG, Andrews LS. Matrix Infrared Spectroscopic Studies of B-NCCN, B- η2-(NC)-CN, NCBCN, CNBCN, CNBNC, and High-Order Products Produced in Reactions of Boron Atoms with Cyanogen. J Phys Chem A 2021; 125:6189-6197. [PMID: 34255520 DOI: 10.1021/acs.jpca.1c04437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The products in reactions of laser-ablated boron atoms with cyanogen in excess argon have been identified via investigation of the matrix spectra and their variation on photolysis, annealing, and isotopic substitutions. DFT calculations have been performed for the plausible products and reaction paths, providing helpful guides. B-NCCN and B-η2-(NC)-CN were observed in the original deposition spectra, but they disappear on photolysis with λ > 220 nm while more stable NCBCN, CNBCN, and CNBNC were produced. Besides these primary products, high-order products [(NC)2B-NCCN, (CN)(NC)B-NCCN, (CN)2B-NCCN, and (NC)2B-B(CN)2] were also observed, which increased in the later stage of annealing. Our calculations show that initially produced B-NCCN is interconvertible to B-η2-(NC)-CN and the more stable boron cyanide and isocyanide, consistent with the observed results. The formation of high-order products demonstrates that boron highly prefers the trivalent state in reactions with cyanogen, similar to aluminum.
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Affiliation(s)
- Han-Gook Cho
- Department of Chemistry, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon 22012, South Korea
| | - Lester S Andrews
- Department of Chemistry, University of Virginia, P.O. Box 400319, Charlottesville, Virginia 22904-4319, United States
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5
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Cho HG, Andrews LS. Matrix Infrared Spectroscopic and Theoretical Investigations of M···NCCN, M···CNCN, M···C( N)CN, NCMCN, CNMNC, CNMCN, and [M···NCCN] + Produced in the Reactions of Group 11 Metal Atoms with Cyanogen. Inorg Chem 2021; 60:6421-6432. [PMID: 33856808 DOI: 10.1021/acs.inorgchem.1c00132] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Reactions of group 11 metals with cyanogen, N≡C-C≡N, in excess argon and neon have been carried out, and the products were identified via examination of the matrix spectra and their variation upon photolysis, annealing, and isotopic substitutions. Density functional theory calculations provided helpful information for the plausible products and reaction paths. While M···NCCN and M···CNCN were observed in all three metal systems, the cyanide and isocyanide products (NCMCN, NCMNC, and CNMNC) were identified only in the Cu reactions, and M···C(N)CN was identified in the Cu and Au spectra. Intrinsic reaction coordinate calculation results along with the observed spectral variation upon photolysis and annealing suggest that Cu···C(N)CN was the pathway to cyanide and isocyanide. The product absorptions with exceptionally high C-N stretching frequencies in the Au system have been tentatively assigned to a cation [Au···NCCN+]. The group 11 metal cyanides and isocyanides that require two chemical bonds to the central metal are energetically favorable only in the lightest metal system.
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Affiliation(s)
- Han-Gook Cho
- Department of Chemistry, Incheon National University, 119 Academy-ro, Yeonsu-gu, Incheon 22012, South Korea
| | - Lester S Andrews
- Department of Chemistry, University of Virginia, P.O. Box 400319, Charlottesville, Virginia 22904-4319, United States
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6
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Jiang J, Du Z, Field RW. Determination of the sign of the population difference in a two-level system by frequency-modulation spectroscopy. Mol Phys 2020. [DOI: 10.1080/00268976.2019.1660007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Jun Jiang
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Zhenhui Du
- State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin, People's Republic of China
| | - Robert W. Field
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
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7
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Photodissociation transition states characterized by chirped pulse millimeter wave spectroscopy. Proc Natl Acad Sci U S A 2020; 117:146-151. [PMID: 31852828 DOI: 10.1073/pnas.1911326116] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The 193-nm photolysis of CH2CHCN illustrates the capability of chirped-pulse Fourier transform millimeter-wave spectroscopy to characterize transition states. We investigate the HCN, HNC photofragments in highly excited vibrational states using both frequency and intensity information. Measured relative intensities of J = 1-0 rotational transition lines yield vibrational-level population distributions (VPD). These VPDs encode the properties of the parent molecule transition state at which the fragment molecule was born. A Poisson distribution formalism, based on the generalized Franck-Condon principle, is proposed as a framework for extracting information about the transition-state structure from the observed VPD. We employ the isotopologue CH2CDCN to disentangle the unimolecular 3-center DCN elimination mechanism from other pathways to HCN. Our experimental results reveal a previously unknown transition state that we tentatively associate with the HCN eliminated via a secondary, bimolecular reaction.
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8
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Gunthardt CE, Aardema MN, Hall GE, North SW. Evidence for lambda doublet propensity in the UV photodissociation of ozone. J Chem Phys 2019; 151:224302. [PMID: 31837678 DOI: 10.1063/1.5131504] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The photodissociation of O3 at 266 nm has been studied using velocity mapped ion imaging. We report temperature-dependent vector correlations for the O2(a1Δg, v = 0, j = 18-20) fragments at molecular beam temperatures of 70 K, 115 K, and 170 K. Both the fragment spatial anisotropy and the v-j correlations are found to be increasingly depolarized with increasing beam temperature. At all temperatures, the v-j correlations for the j = 19 state were shown to be reduced compared to those of j = 18 and 20, while no such odd/even rotational state difference was observed for the spatial anisotropy, consistent with previous measurements. We find that temperature-dependent differences in the populations and v-j correlations between the odd and even rotational states can be explained by a Λ-doublet propensity model. Although symmetry conservation should lead to formation of only the A' Λ-doublet component, and only even rotational states, out-of-plane rotation of the parent molecule breaks the planar symmetry and permits the formation of the A″ Λ-doublet component and odd rotational states. A simple classical model to treat the effect of parent rotation on the v-j correlation and the odd/even rotational population alternation reproduces both the current measurements and previously reported rotational distributions, suggesting that the "odd" behavior originates from a Λ-doublet propensity, and not from a mass independent curve crossing effect, as previously proposed.
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Affiliation(s)
- Carolyn E Gunthardt
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
| | - Megan N Aardema
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
| | - Gregory E Hall
- Chemistry Division, Brookhaven National Laboratory P.O. Box 5000 Upton, New York 11973-5000, USA
| | - Simon W North
- Department of Chemistry, Texas A&M University, College Station, Texas 77842, USA
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9
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Halpern JB. The C ̃ 1B u ← X ̃ 1Σ g+ Transition of Ethanedinitrile (C 2N 2): Assignment of the Electronic State Origin and Vibrational Bands. J Phys Chem A 2018; 122:7790-7796. [DOI: 10.1021/acs.jpca.8b06235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Joshua B. Halpern
- Department of Chemistry, Howard University, Washington, DC 20059, United States
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10
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Lourderaj U, Hase WL. Theoretical and Computational Studies of Non-RRKM Unimolecular Dynamics. J Phys Chem A 2009; 113:2236-53. [DOI: 10.1021/jp806659f] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Upakarasamy Lourderaj
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061
| | - William L. Hase
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, Texas 79409-1061
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11
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Suits AG, Chambreau SD, Lahankar SA. State-correlated DC slice imaging of formaldehyde photodissociation: roaming atoms and multichannel branching. INT REV PHYS CHEM 2007. [DOI: 10.1080/01442350701589908] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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12
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Suter HU, Pfister R, Furlan A, Huber JR. Dissociation and Recombination in the Photochemical Decay of Carbonyl Cyanide CO(CN)2 in Cryogenic Matrixes. J Phys Chem A 2007; 111:764-9. [PMID: 17266215 DOI: 10.1021/jp065731l] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The photochemistry of CO(CN)2 in cryogenic matrixes has been investigated employing pulsed laser excitation at 193 nm. During irradiation, the parent molecule, the intermediate, and the final photoproducts were monitored by IR spectroscopy. Four new species were identified including the isocyano isomer of the parent NCC(O)NC, cyanogen NCCN, isocyanogen CNCN, and CO according to spectroscopic features and ab initio calculations. After prolonged irradiation, the only remaining species were CO and the two isomers NCCN and CNCN. A reaction scheme is proposed which is in agreement with the first dissociation step being a branching of the decay path into the radical channel to CN+OCCN and the molecular channel to CO+(CN)2. The caged radicals of the former reaction either recombine to the parent molecule and its isomer which are both photolyzed again or they react directly to the stable and final products.
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Affiliation(s)
- H U Suter
- Physikalisch-Chemisches Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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13
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Abstract
The vast majority of chemical reactions involve polyatomic species as reactants and/or products. The added degree of complexity offers opportunities to address dynamical questions other than those already encountered in a typical atom + diatom reaction. Product pair correlation is one of them. This article introduces the basic concept, outlines the experimental approach we developed and then highlights some of the applications to bimolecular reaction dynamics. Particular emphasis is placed on the information contents and unique insights gained from this type of measurements, which otherwise would have been lost by the conventional approach.
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Affiliation(s)
- Kopin Liu
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, P.O. Box 23-166, Taipei, 10617, Taiwan
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14
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Alagappan A, Ballingall I, Costen ML, McKendrick KG, Paterson G. Efficiencies of state and velocity-changing collisions of superthermal CN A2Π with He, Ar, N2and O2. Phys Chem Chem Phys 2007; 9:747-54. [PMID: 17268687 DOI: 10.1039/b614965k] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Polarized laser photolysis of ICN is combined with saturated optical pumping to prepare state-selected CN Alpha(2)Pi (nu' = 4, J = 0.5, F(2), f) with a well-defined anisotropic superthermal speed distribution. The collisional evolution of the prepared state is observed by Doppler-resolved Frequency Modulated (FM) spectroscopy via stimulated emission on the CN Alpha(2)Pi-Chi(2)Sigma(+) (4,2) band. The phenomenological rate constants for removal of the prepared state in collisions with He, Ar, N(2) and O(2) are reported. The observed collision cross-sections are consistent with attractive forces contributing significantly for all the colliders with the exception of He. The collisional evolution of the prepared velocity distribution demonstrates that no significant back-transfer into the prepared level occurs, and that any elastic scattering is strongly in the forward hemisphere.
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Affiliation(s)
- Azhagammai Alagappan
- School of Engineering and Physical Sciences, William H Perkin Building, Heriot-Watt University, Edinburgh, UK
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15
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Zhang B, Shiu W, Lin JJ, Liu K. Mode correlation of product pairs in the reaction OH+CD4→HOD+CD3. J Chem Phys 2005; 122:131102. [PMID: 15847448 DOI: 10.1063/1.1885466] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The hydrogen abstraction reaction from methane by a hydroxyl radical produces two polyatomic molecules. Each product has several vibrational modes that characterize distinct, concerted motions of the constituent atoms of the molecule. This communication describes the first measurement that maps out the coincident information on how the mode of excitation of one product varies with that of the other co-product. Such information on mode correlation of product pairs is particularly appealing in that it provides intuitively a glimpse of the reaction paths by which the chemical transformation occurs.
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Affiliation(s)
- Bailin Zhang
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, P.O. Box 23-166, Taipei, Taiwan 106
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16
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Decker BK, Macdonald RG. Determination of the Rate Constant for the Radical−Radical Reaction CN(X2Σ+) + OH(X2Π) at 292 K. J Phys Chem A 2003. [DOI: 10.1021/jp030591q] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Brian K. Decker
- Argonne National Laboratory, Chemistry Division, 9700 South Cass Avenue, Argonne, Illinois 60439-4831
| | - R. Glen Macdonald
- Argonne National Laboratory, Chemistry Division, 9700 South Cass Avenue, Argonne, Illinois 60439-4831
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17
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Gao Y, Macdonald RG. Determination of the Rate Constant for the NCO(X2Π) + O(3P) Reaction at 292 K. J Phys Chem A 2003. [DOI: 10.1021/jp0222595] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yide Gao
- Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439-4831
| | - R. Glen Macdonald
- Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439-4831
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18
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McGivern WS, North SW. Treatment of the K-quantum number in unimolecular reaction theory: insights from product correlations. J Am Chem Soc 2002; 124:14472-7. [PMID: 12452724 DOI: 10.1021/ja0273602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The connection between the K-quantum number and product correlations in the barrierless unimolecular dissociation of symmetric-top molecules is explored to establish a qualitative diagnostic for the treatment of the K-rotor dynamics in unimolecular reaction theory. We find that fragment scalar and vector correlations can provide guidance in this matter, and the photodissociation dynamics of thermal NCNO to form CN and NO at several dissociation wavelengths are presented to demonstrate the utility of this approach. The "goodness" of the K-quantum number can be related to the amount of energy in the conserved vibrational modes at the inner transition state. On the basis of measured correlated vibrational distributions, the K-quantum number is found to be approximately conserved at the inner transition state for the photodissociation of NCNO at 514, 520, and 526 nm. The methodology, involving a comparison of product distributions from the photodissociation of jet and thermal ensembles at identical wavelengths, is general and may be applied to previously studied systems that dissociate along barrierless potential energy surfaces, CF(3)NO and CH(2)CO. In addition, vector correlations serve as a means to probe the K-mixing at the outer transition state, and measured v-j correlations in the photodissociation of thermal NCNO are presented.
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Affiliation(s)
- W Sean McGivern
- Department of Chemistry, Texas A&M University, 3255 TAMU, College Station, Texas 77842, USA
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19
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McGivern WS, North SW. Probing the nature of the K-rotor in unimolecular reactions: Scalar and vector correlations in the photodissociation of NCNO. J Chem Phys 2002. [DOI: 10.1063/1.1462581] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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20
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Affiliation(s)
- H Sato
- Laser Photochemistry Research Group, Department of Chemistry for Materials, Faculty of Engineering, Mi'e University, 1515 Kamihamacho, Tsu 514-8507, Japan.
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21
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Abstract
Explicitly time-dependent implementations of optical frequency modulation spectroscopy have been recently applied to a wide range of problems in chemical physics. We provide a brief description of the methodology, with an emphasis on its intrinsic advantages for interrogating transient species. Several examples highlight the application of the technique to high-resolution absorption spectra of free radicals, rate measurements for gas-phase reactions, and Doppler spectroscopy of the gas-phase products of photoinitiated reactions.
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Affiliation(s)
- G E Hall
- Chemistry Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
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22
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Macdonald RG. Rotational and Vibrational State Distributions of HNC(0 0) from the Hot H Atom Reaction: H + (CN)2 → HNC + CN. J Phys Chem A 2000. [DOI: 10.1021/jp0010583] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- R. Glen Macdonald
- Argonne National Laboratory, Chemistry Division, 9700 South Cass Ave., Argonne, Illinois 60439
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23
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He G, Tokue I, Macdonald RG. Rotational and translational energy distributions of CN(v=0,J) from the hot atom reactions: H+XCN→HX+CN(v=0,J), where X=Br, Cl, and CN. J Chem Phys 2000. [DOI: 10.1063/1.481243] [Citation(s) in RCA: 6] [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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24
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Li R, Derecskei-Kovacs A, North SW. The unimolecular dissociation of 2-butenenitrile: measurements of the CN elimination channel using FM Doppler spectroscopy. Chem Phys 2000. [DOI: 10.1016/s0301-0104(00)00050-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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25
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Costen ML, North SW, Hall GE. Vector signatures of adiabatic and diabatic dynamics in the photodissociation of ICN. J Chem Phys 1999. [DOI: 10.1063/1.480041] [Citation(s) in RCA: 52] [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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26
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Scheld HA, Furlan A, Huber JR. The photodissociation of carbonyl cyanide CO(CN)2 at 193 nm studied by photofragment translational energy spectroscopy. J Chem Phys 1999. [DOI: 10.1063/1.479376] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
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27
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Spasov JS, Cline JI. Scalar and angular correlations in CF3NO photodissociation: statistical and nonstatistical channels. J Chem Phys 1999. [DOI: 10.1063/1.478922] [Citation(s) in RCA: 6] [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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28
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He G, Seth M, Tokue I, Macdonald RG. Experimental and theoretical determination of the magnetic dipole transition moment for the Br(4p5)(2P1/2←2P3/2) fine-structure transition and the quantum yield of Br(2P1/2) from the 193 nm photolysis of BrCN. J Chem Phys 1999. [DOI: 10.1063/1.478689] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [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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He G, Tokue I, Macdonald RG. Experimental measurement of the transition moment for the (2,0) band of the CN A 2Π←X 2Σ+ red system at 789.5 nm. J Chem Phys 1998. [DOI: 10.1063/1.477273] [Citation(s) in RCA: 11] [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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Bethardy GA, Northrup FJ, He G, Tokue I, Macdonald RG. Initial vibrational level distribution of HCN[X̃ 1Σ+(v10v3)] from the CN(X 2Σ+)+H2→HCN+H reaction. J Chem Phys 1998. [DOI: 10.1063/1.477028] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
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He G, Tokue I, Harding LB, Macdonald RG. Thermal Rate Constant and Branching Ratio for CN + HD → HCN/DCN + D/H from T = 293 to 375 K. J Phys Chem A 1998. [DOI: 10.1021/jp982391y] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- G. He
- Argonne National Laboratory, Chemistry Division, 9700 South Cass Ave., Argonne, Illinois 60439
| | - I. Tokue
- Argonne National Laboratory, Chemistry Division, 9700 South Cass Ave., Argonne, Illinois 60439
| | - Lawrence B. Harding
- Argonne National Laboratory, Chemistry Division, 9700 South Cass Ave., Argonne, Illinois 60439
| | - R. Glen Macdonald
- Argonne National Laboratory, Chemistry Division, 9700 South Cass Ave., Argonne, Illinois 60439
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He G, Tokue I, Macdonald RG. Thermal Rate Constant for CN + H2/D2 → HCN/DCN + H/D Reaction from T = 293 to 380 K. J Phys Chem A 1998. [DOI: 10.1021/jp980875o] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- G. He
- Argonne National Laboratory, Chemistry Division, 9700 South Cass Ave., Argonne, Illinois 60565
| | - I. Tokue
- Argonne National Laboratory, Chemistry Division, 9700 South Cass Ave., Argonne, Illinois 60565
| | - R. Glen Macdonald
- Argonne National Laboratory, Chemistry Division, 9700 South Cass Ave., Argonne, Illinois 60565
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Marr AJ, North SW, Sears TJ, Ruslen L, Field RW. Laser Transient Absorption Spectroscopy of Bromomethylene. JOURNAL OF MOLECULAR SPECTROSCOPY 1998; 188:68-77. [PMID: 9480803 DOI: 10.1006/jmsp.1997.7500] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We report the observation and assignment of new high-resolution spectra of the A1A" <-- X1A' transition of bromomethylene, HCBr, obtained by transient laser absorption spectroscopy at near-infrared wavelengths. The 2(1)0 band of HCBr (nu0 = 11 957 cm-1) and the 2(2)0 band of DCBr (nu0 = 12 349 cm-1) have been observed for both naturally occurring isotopes of bromine. The c-type rotational branches of the Ka = 0 <-- 1 subbands have been assigned in detail. Other subbands have been partially assigned, but their detailed rotational quantum number analysis has not yet proved possible. Their presence does, however, indicate that the molecule exhibits nonlinear rotational structure in these vibrational levels, in contrast to what was found for the A1A" (0, 2, 0) level of HCBr (nu0 = 12 786 cm-1) [B. C. Chang and T. J. Sears, J. Chem. Phys. 105, 2135-2140 (1996)]. Analysis of the rotational structure in the spectra reported here has required a reassessment of certain rotational assignments of that previous work. We now find that the lower singlet state is isolated; there is no evidence of triplet state perturbations. Rotational constants derived for the ground state of all the naturally occurring isotopomers were used to estimate structural parameters. A barrier to linearity for the A1A" state, 13 590 cm-1 above the zero point level of the ground X1A' state, is estimated. Copyright 1998 Academic Press.
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Affiliation(s)
- AJ Marr
- Department of Chemistry, Brookhaven National Laboratory, Upton, New York, 11973-5000
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Song K, Hase WL. Role of State Specificity in the Temperature- and Pressure-Dependent Unimolecular Rate Constants for HO2 → H + O2 Dissociation. J Phys Chem A 1998. [DOI: 10.1021/jp972581t] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kihyung Song
- Department of Chemistry, Korea National University of Education, Chungbuk 363-791, South Korea, and Department of Chemistry, Wayne State University, Detroit, Michigan 48202
| | - William L. Hase
- Department of Chemistry, Korea National University of Education, Chungbuk 363-791, South Korea, and Department of Chemistry, Wayne State University, Detroit, Michigan 48202
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North SW, Marr AJ, Furlan A, Hall GE. Nonintuitive Asymmetry in the Three-Body Photodissociation of CH3COCN. J Phys Chem A 1997. [DOI: 10.1021/jp972293x] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Simon W. North
- Chemistry Department, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973-5000, and Physikalisch-Chemisches Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Andrew J. Marr
- Chemistry Department, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973-5000, and Physikalisch-Chemisches Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Alan Furlan
- Chemistry Department, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973-5000, and Physikalisch-Chemisches Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Gregory E. Hall
- Chemistry Department, Brookhaven National Laboratory, P.O. Box 5000, Upton, New York 11973-5000, and Physikalisch-Chemisches Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
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