Time-resolved infrared study of bimolecular reactions between t
 e
 r
 t-butyl radicals

Bethune, Donald S.; Lankard, J. R.; Sorokin, P. P.; Schell-Sorokin, A. J.; Plecenik, R. M.; Avouris, Phaedon

doi:10.1063/1.442336

Cited by 24 publications

(7 citation statements)

References 19 publications

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“…For clarity the experimental data prior to 1976 95,[114][115][116][117][118][119][120][121][122] are not plotted. Again, the dynamically corrected VRC-TST predictions are in quantitative agreement with the direct experimental observations from Shafir et al 113 Plots of the theoretical predictions and experimental measurements of the capture rate for the iso-propyl 96,103,119,120,[123][124][125][126] and tert-butyl 96,103,110,119,120,123,[127][128][129][130][131] self combination reactions are provided in Fig. 10 and 11.…”

Section: Tests For Ch 3 þ Chsupporting

confidence: 71%

Predictive theory for the combination kinetics of two alkyl radicals

Klippenstein

Georgievskii

Harding

2006

Phys. Chem. Chem. Phys.

212

272

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An ab initio transition state theory based procedure for accurately predicting the combination kinetics of two alkyl radicals is described. This procedure employs direct evaluations of the orientation dependent interaction energies at the CASPT2/cc-pvdz level within variable reaction coordinate transition state theory (VRC-TST). One-dimensional corrections to these energies are obtained from CAS+1+2/aug-cc-pvtz calculations for CH3 + CH3 along its combination reaction path. Direct CAS+1+2/aug-cc-pvtz calculations demonstrate that, at least for the purpose of predicting the kinetics, the corrected CASPT2/cc-pvdz potential energy surface is an accurate approximation to the CAS+1+2/aug-cc-pvtz surface. Furthermore, direct trajectory simulations, performed at the B3LYP/6-31G* level, indicate that there is little local recrossing of the optimal VRC transition state dividing surface. The corrected CASPT2/cc-pvdz potential is employed in obtaining direct VRC-TST kinetic predictions for the self and cross combinations of methyl, ethyl, iso-propyl, and tert-butyl radicals. Comparisons with experiment suggest that the present dynamically corrected VRC-TST approach provides quantitatively accurate predictions for the capture rate. Each additional methyl substituent adjacent to a radical site is found to reduce the rate coefficient by about a factor of two. In each instance, the rate coefficients are predicted to decrease quite substantially with increasing temperature, with the more sterically hindered reactants having a more rapid decrease. The simple geometric mean rule, relating the capture rate for the cross reaction to those for the self-reactions, is in remarkably good agreement with the more detailed predictions. With suitable generalizations the present approach should be applicable to a wide array of radical-radical combination reactions.

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Section: Tests For Ch 3 þ Chsupporting

confidence: 71%

Predictive theory for the combination kinetics of two alkyl radicals

Klippenstein

Georgievskii

Harding

2006

Phys. Chem. Chem. Phys.

212

272

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“…We believe that these features are due to mode competition and resultant quantum noise in the spectral output of the BBD laser systems, which are lasing on many unstabilized modes with different degrees of gain. Similar effects have been observed in the early infrared spectral photography experiments of Bethune et al 10,11 wherein an infrared heat pipe was pumped with the output of a BBD laser system. In cases such as these it is potentially desirable to average a number of events to reduce intensity fluctuations in the RSP image to more tolerable levels.…”

Section: ϫ3supporting

confidence: 65%

“…In this paper we report on the development of a RSP instrument wherein a broadband dye ͑BBD͒ laser system is used to obtain absorption spectra that are due to intracavity species over a large optical bandwidth in a single-shot fashion. The broadband RSP approach integrates the attributes of frequency-multiplexed direct absorption approaches such as the early infrared spectral photography experiments of Bethune et al 10,11 with the first pulsed laser time-domain ringdown experiments demonstrated nearly a decade later by O'Keefe and Deacon. 3 Here, broadband RSP spectra are presented that demonstrate the ability to monitor spectrally broad as well as narrow absorption features in two regions of the visible spectrum.…”

Section: Introductionmentioning

confidence: 99%

Ringdown spectral photography

Scherer¹

1998

Chemical Physics Letters

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A new technique that enables frequency-resolved cavity ringdown absorption spectra to be obtained over a large optical bandwidth by a single laser shot is described. The technique, ringdown spectral photography ͑RSP͒, simultaneously employs two key principles to record the time and frequency response of an optical cavity along orthogonal axes of a CCD array detector. Previously, the principles employed in RSP were demonstrated with narrow-band laser light that was scanned in frequency ͓Chem. Phys. Lett. 292, 143 ͑1998͔͒. Here, the RSP method is demonstrated using single pulses of broadband visible laser light. The ability to obtain broad as well as rotationally resolved spectra over a large bandwidth with high sensitivity is demonstrated.

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“…Color-center laser spectroscopy of transient species produced by excimer-laser flash photolysis INTRODUCTION A powerful method for the detection of transient species is the UV flash photolysis of stable precursor gases and subsequent IR probing of the molecular fragments produced. ", 2 Such experiments can provide three different kinds of information:…”

mentioning

confidence: 99%

“…(1) the absorption spectra of short-lived radicals often in electronically excited states as well as the ground state; (2) chemical kinetic data of the transient species produced; and (3) determination of the nascent distribution of the product states formed. The infrared is an especially interesting region of the spectrum because almost all substances exhibit absorptions in this region, thereby providing a nearly universal monitor of transient species.…”

mentioning

confidence: 99%

Color-center laser spectroscopy of transient species produced by excimer-laser flash photolysis

et al. 1985

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Kinetic spectroscopy based on excimer-laser flash photolysis and color-center-laser (CCL) infrared probing is explored. In simple absorption, the achievable signal-to-noise ratio (S/N) is not satisfactory even though the signal itself (corresponding to >1% absorption) is fairly large. This is due to amplitude fluctuations of the CCL. By using a double-beam detection scheme to balance out these amplitude fluctuations the sensitivity can be improved to the extent that a 1% absorption gives a S/N-100. In certain situations transient decreases in absorption of the precursor and transient increases in absorption due to final product formation can produce severe interfering signals even in simple systems. This problem is overcome without a major loss in sensitivity by a recently developed 450 magnetic rotation scheme. These points are illustrated with spectra of Br, OH, and NH 2 .

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Time-resolved infrared study of bimolecular reactions between t e r t-butyl radicals

Cited by 24 publications

References 19 publications

Predictive theory for the combination kinetics of two alkyl radicals

Predictive theory for the combination kinetics of two alkyl radicals

Ringdown spectral photography

Color-center laser spectroscopy of transient species produced by excimer-laser flash photolysis

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