Correlations of NO rotation and translation produced in the photofragmentation of 2‐chloro‐2‐nitrosopropane via two dissociation channels
摘要:
Correlated rotational and translational product state distributions of the NO X 2Π1/2,3/2 (v=0) product of the dissociation of 2-chloro-2-nitrosopropane in a molecular beam following à 1A″←X̃ 1A′[n(N),π*(N=0)] excitation at 600 and 650 nm are measured by resonance-enhanced multiphoton ionization/time-of-flight mass spectrometry in a molecular beam. The NO speed distribution appears bimodal and the average speed increases with NO rotational quantum number. The slow component of the NO velocity distribution is attributed to dissociation on the S0 surface and the fast component to dissociation across a barrier along the reaction coordinate on the T1 surface. A two-channel dynamical model based on statistical phase space theory is used to model the correlated NO rotational and translational distributions. The experimental data are consistent with a C–N bond energy of 12 900±200 cm−1 on the S0 surface and a barrier height of 1500±200 cm−1 on the T1 surface. The high rotational excitation of NO products originating on the T1 surface can be attributed to impulsive recoil of NO from a bent C–N–O geometry atop the T1 barrier.
Correlations of NO rotation and translation produced in the photofragmentation of 2‐chloro‐2‐nitrosopropane via two dissociation channels
作者:Jeffrey L. Tomer、Mark C. Wall、Brian P. Reid、Joseph I. Cline
DOI:10.1063/1.469344
日期:1995.4.15
Correlated rotational and translational product state distributions of the NO X 2Π1/2,3/2 (v=0) product of the dissociation of 2-chloro-2-nitrosopropane in a molecular beam following à 1A″←X̃ 1A′[n(N),π*(N=0)] excitation at 600 and 650 nm are measured by resonance-enhanced multiphoton ionization/time-of-flight mass spectrometry in a molecular beam. The NO speed distribution appears bimodal and the average speed increases with NO rotational quantum number. The slow component of the NO velocity distribution is attributed to dissociation on the S0 surface and the fast component to dissociation across a barrier along the reaction coordinate on the T1 surface. A two-channel dynamical model based on statistical phase space theory is used to model the correlated NO rotational and translational distributions. The experimental data are consistent with a C–N bond energy of 12 900±200 cm−1 on the S0 surface and a barrier height of 1500±200 cm−1 on the T1 surface. The high rotational excitation of NO products originating on the T1 surface can be attributed to impulsive recoil of NO from a bent C–N–O geometry atop the T1 barrier.
NO <b>v</b>–<b>j</b> vector correlations in the photodissociation of 2‐chloro‐2‐nitrosopropane
作者:Radoslaw Uberna、Joseph I. Cline
DOI:10.1063/1.469519
日期:1995.3.15
The correlation between the velocity and angular momentum vectors of the NO X 2ΠΩ=1/2,3/2(v=0) fragment from the photodissociation of 2-chloro-2-nitrosopropane, CH3CCl(NO)CH3, following excitation to the S1Ã 1A″ electronic surface is measured. The experiments are performed in a molecular beam and a scheme for detecting NO by polarized 1+1′ resonance-enhanced multiphoton ionization and pulsed-extraction time-of-flight mass spectrometry is described. The vector correlation is a function of the NO rotational state j, and the bipolar moment describing the correlation has a maximum value of β00(22)=−0.13(±0.01) at j≊18.5–22.5, indicating a preferred perpendicular orientation of the NO angular momentum and velocity vectors. The correlation diminishes as j decreases. This result is consistent with impulsive dissociation from a barrier along the reaction coordinate on the T1ã 3A″ surface, previously postulated to produce the highest angular momentum states of NO.
WANG, BING-ZE;DENG, CONG-HAO, XUASYUEH SYUEHBAO, 46,(1988) N2, S. 1155-1160
作者:WANG, BING-ZE、DENG, CONG-HAO
DOI:——
日期:——
NO μ‐v‐j correlations in the photofragmentation of 2‐chloro‐2‐nitrosopropane
作者:Radoslaw Uberna、Robert D. Hinchliffe、Joseph I. Cline
DOI:10.1063/1.472935
日期:1996.12.8
The trajectory of NO X 2ΠΩ=1/2,3/2(v=0) produced after excitation of 2-chloro-2-nitrosopropane S1 Ã 1A″ is studied by polarized 1+1′ resonance-enhanced multiphoton ionization with time-of-flight mass spectrometry detection. The correlations among the NO velocity v, angular momentum j, and the S1 Ã 1A″←S0 X̃ 1A′ [n(N),π*(N=O)] transition dipole μ of the parent molecule are measured. The dissociation occurs by internal conversion to the ground S0 state or intersystem crossing to the T1 ã 3A″ state and the observed speed distribution of the NO fragments is bimodal. There is no evidence for μ-v-j correlations for the products associated with the slow component of the speed distribution. For the higher speed component, the v-j correlation is a function of the NO rotational state, j, and is described by the bipolar moment β00(22). The average value of β00(22) is −0.17(±0.02) at j≊11.5–22.5, more than five times larger than predicted by statistical phase space theory for dissociation on the S0 X̃ 1A′ surface, indicating a moderate preference for a perpendicular orientation of the NO rotational angular momentum and velocity vectors. The v and j vectors are nearly uncorrelated for low NO rotational states (j≤6.5). The μ-v correlation described by the β20(20) bipolar moment does not change with j and its average value is −0.04(±0.01) at j≊12.5–19.5. The average value of the β20(02) bipolar moment describing μ-j correlation is 0.04(±0.02) at j≊7.5–24.5. These results are consistent with a mechanism involving both impulsive force due to a barrier along the reaction coordinate on the T1 ã 3A″ surface and forces resulting from the C–N–O bending and NO torsion about the C–N bond.