Crossed Beam Rovibrational Energy Transfer from S1 Glyoxal. 2. Uniform Scattering Characteristics from the Initial Levels O0, 51, and 81

Gilbert, B.; Parmenter, C. S.; Krajnovich, D.

doi:10.1021/j100080a004

Cited by 11 publications

(22 citation statements)

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“…23 Much of the recent interest in this molecule stems from its presence in the polluted tropospheric atmosphere 24,25 and as an intermediate in combustion systems. 26 Its well-characterized spectrum has led to further studies using this molecule to probe collisional energy transfer processes, [27][28][29][30][31][32][33][34][35][36] molecular alignment, 37 predissociation of van der Waals complexes, [38][39][40] and stimulated emission pumping. 39,41,42 Following the first observations of collisionless predissociation of glyoxal, [43][44][45] the dissociation dynamics of this molecule have also been examined.…”

Section: Introductionmentioning

confidence: 99%

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H₂ Production in the 440-nm Photodissociation of Glyoxal

et al. 1999

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H 2 has been detected following the photolysis of glyoxal at 440 nm using the techniques of vacuum ultraviolet laser-induced fluorescence and (2 + 1) resonance enhanced multiphoton ionization. It is thus confirmed that a fraction of the glyoxal excited at this wavelength dissociates into three photofragments: HCOCOH f H 2 + 2 CO. The most populated vibrational level of those observed was H 2 (V ) 1), and in this level rotational states from J ) 0-9 were detected. Doppler profiles of these lines provide estimates of the translational energy and show a v||J correlation. Of the available energy to the H 2 + 2CO products, 3.1% appears as rotational energy in H 2 (V ) 1), 17.8% appears as the H 2 (V ) 1) vibration, and 46.8% appears as H 2 (V ) 1) translation. Excitation of the 7 0 2 band produces somewhat more of the H 2 + 2CO channel than does excitation of the 0 0 0 , 5 0 1 , or 8 0 1 bands. These observations are consistent with a model in which transfcis isomerization precedes dissociation. Rotational excitation with v||J is caused by the V 7 torsional motion. The small degree of rotational excitation, the production of H 2 in V ) 1 and V ) 2, and the translational energy distribution are all consistent with ab initio calculations of the transition state structure.

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Section: Introductionmentioning

confidence: 99%

“…Much of the recent interest in this molecule stems from its presence in the polluted tropospheric atmosphere , and as an intermediate in combustion systems − molecular alignment, predissociation of van der Waals complexes, − and stimulated emission pumping. ,, …”

Section: Introductionmentioning

confidence: 99%

H₂ Production in the 440-nm Photodissociation of Glyoxal

et al. 1999

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“…So far, the studies have involved energy transfer from each of four initial rovibrational levels in the S 1 state encompassing three different modes. − For three of these initial levels, over 20 state-to-state channels are monitored. For the fourth level, the competition can be followed among almost 50 channels.…”

Section: Introductionmentioning

confidence: 99%

State-to-State Inelastic Scattering from S₁ Glyoxal with the Rare Gas Series: Uniform Rotational vs Changing Vibrational Channel Competition

1998

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To provide data for the complete series of rare gases, relative cross sections are obtained for the crossed molecular beam state-to-state rotationally and rovibrationally inelastic scattering of S1 (1Au) glyoxal (CHO−CHO) in its 00, K‘ = 0 states by Ne, Ar, and Xe. When added to cross sections from a new analysis of Kr data and to published data for H2 and He, sets of cross sections for the entire rare gas series are available that show the competition among more than 25 rotational and rovibrational channels. The latter all involve Δυ7‘ = +1 where ν7‘ = 233 cm-1 is the lowest frequency mode. Despite large variations in the collisional kinematics and in the interaction potential energy surfaces, the competition among rotationally inelastic channels is essentially identical for the gases Ne, Ar, Kr, and Xe. In turn, those cases differ from H2 and He solely by the fact that orbital angular momentum constraints with the light gases limit scattering to only those states with ΔK ≲ 15. In contrast, the competition between rotational and rovibrational scattering changes with the collision partner to the extent that state-to-state resolution of rovibrational scattering is not possible for Ar, Kr, and Xe. Previous theoretical predictions for Ar inelastic scattering are consistent with earlier arguments that this competition is dominated by kinematic factors rather than by variations in the interaction potential. The relative cross sections are obtained from experiments in which a laser prepares S1 glyoxal in the 00 K‘ = 0 state with J‘ ≈ 0−10. Dispersed S1−S0 fluorescence is used to monitor the inelastic scattering to more than 25 destination states with ΔK‘ resolution. Inelastic cross sections are extracted by computer simulation of the fluorescence spectra.

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“…In this paper, we discuss collisional energy transfer involving glyoxal (CHO-CHO), a 12-mode molecule that has been under study for some time. Crossed molecular beams coupled with S 1 -S 0 laser pumping and a dispersed fluorescence probe are used to observe state-to-state rotational and rovibrational inelastic scattering in the S 1 excited electronic state (6)(7)(8)(9)(10). The state resolution is sufficient to see the competition between many rotational and rovibrational channels.…”

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confidence: 99%

“…Experiments using the collision partner He have already been reported for each of the initial levels shown in bold in Fig. 1 (8,9). They include the zero point level, both in-plane and out-of-plane fundamentals and an overtone of the CHOCHO torsion, 7 .…”

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Factors controlling the competition among rotational and vibrational energy transfer channels in glyoxal

Parmenter

Clegg

Krajnovich

et al. 1997

Proc. Natl. Acad. Sci. U.S.A.

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The state-to-state transfer of rotational and vibrational energy has been studied for S 1 glyoxal (CHOCHO) in collisions with D 2 , N 2 , CO and C 2 H 4 using crossed molecular beams. A laser is used to pump glyoxal seeded in He to its S 1 zero point level with zero angular momentum about its top axis (K ‫؍‬ 0). The inelastic scattering to each of at least 26 S 1 glyoxal rotational and rovibrational levels is monitored by dispersed S 1 -S 0 f luorescence. Various collision partners are chosen to investigate the relative inf luences of reduced mass and the collision pair interaction potential on the competition among the energy transfer channels. When the data are combined with that obtained previously from other collision partners whose masses range from 2 to 84 amu, it is seen that the channel competition is controlled primarily by the kinematics of the collisional interaction. Variations in the intermolecular potential play strictly a secondary role.Vibrational and rotational energy transfer during molecular collisions is a venerable subject whose study may be traced back to nearly the beginning of this century (ref. 1; note that in this reference the history is traced to the 1911 papers by J. Franck and R. W. Wood). Its durability is testament to its fundamental role in chemical reactivity as well as to its experimental challenges. For example, consider a molecule with 10 vibrational modes in some initial vibrational state that is in collision with the simplest of partners, He. We may ask a most basic question. What is the probability of populating each of the neighboring vibrational levels in a single collision? The answers to this seemingly elementary enquiry began to emerge only within the last two decades, and they are still limited to only a few molecules, mostly aromatics (2, 3). More recently, a new level of detail has been added to the question. Suppose we are able to select a narrow distribution of initial rotational states within a vibrational state. Now rotational as well as vibrational resolution enters the study.Experiments with rotational resolution are made possible by the use of crossed molecular beams (4, 5). In this paper, we discuss collisional energy transfer involving glyoxal (CHO-CHO), a 12-mode molecule that has been under study for some time. Crossed molecular beams coupled with S 1 -S 0 laser pumping and a dispersed fluorescence probe are used to observe state-to-state rotational and rovibrational inelastic scattering in the S 1 excited electronic state (6-10). The state resolution is sufficient to see the competition between many rotational and rovibrational channels.In the present study, we focus on an exploration of the relative importance of factors that influence this channel competition. Specifically, we have chosen sets of collision partners that allow comparison of the effects due to changes in the intermolecular potential energy surface with the kinematic effects associated with the reduced mass of the collision pair. The comparisons are made by examining the inelasti...

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Crossed Beam Rovibrational Energy Transfer from S1 Glyoxal. 2. Uniform Scattering Characteristics from the Initial Levels O0, 51, and 81

Cited by 11 publications

References 3 publications

H₂ Production in the 440-nm Photodissociation of Glyoxal

H₂ Production in the 440-nm Photodissociation of Glyoxal

State-to-State Inelastic Scattering from S₁ Glyoxal with the Rare Gas Series: Uniform Rotational vs Changing Vibrational Channel Competition

Factors controlling the competition among rotational and vibrational energy transfer channels in glyoxal

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Crossed Beam Rovibrational Energy Transfer from S1 Glyoxal. 2. Uniform Scattering Characteristics from the Initial Levels O0, 51, and 81

Cited by 11 publications

References 3 publications

H2 Production in the 440-nm Photodissociation of Glyoxal

H2 Production in the 440-nm Photodissociation of Glyoxal

State-to-State Inelastic Scattering from S1 Glyoxal with the Rare Gas Series: Uniform Rotational vs Changing Vibrational Channel Competition

Factors controlling the competition among rotational and vibrational energy transfer channels in glyoxal

Contact Info

Product

Resources

About

H₂ Production in the 440-nm Photodissociation of Glyoxal

H₂ Production in the 440-nm Photodissociation of Glyoxal

State-to-State Inelastic Scattering from S₁ Glyoxal with the Rare Gas Series: Uniform Rotational vs Changing Vibrational Channel Competition