Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (07): 1903-1908.doi: 10.3866/PKU.WHXB20100630

• PHOTOCHEMISTRY AND SPECTROSCOPY • Previous Articles     Next Articles

Photolysis of n-C3H7I and i-C3H7I at 266 nm: Effect of Alkyl Radical Branching on the Dissociation Dynamics of the C—I Bond

ZHANG Feng, WANG Yan-Mei, ZHANG Bing, FENG Wen-Lin   

  1. School of Optoelectronic Information, Chongqing University of Technology, Chongqing 400051, P. R. China
    State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, P. R. China
    Graduate University of Chinese Academy of Sciences, Beijing 100049, P. R. China
  • Received:2010-03-02 Revised:2010-04-05 Published:2010-07-02
  • Contact: ZHANG Bing E-mail:bzhang@wipm.ac.cn

Abstract:

Photodissociation dynamics of n-C3H7I and i-C3H7I at 266 nm were investigated using an ion imaging technique combined with resonance enhanced multiphoton ionization (REMPI). Information on energy disposal and a nonadiabatic transition between the dissociative electronic states involved in the photodissociation of both molecules were analyzed and compared. The fraction of internal energy in the I channel is greater than that in the I* channel for both molecules. As the alkyl group becomes more branched the energy distribution of the atom fragments (I and I*) becomes obviously wider suggesting that the alkyl radical at the α-carbon atomhas more complicated models of the ro-vibration models. On the other hand, the relative oscillator strengths of these molecules that were pumped using 266 nm photons show a small difference in the 3Q0←X transition. The probability of yielding an I* fragment decreases markedly from 0.72 for n-C3H7I to 0.46 for i-C3H7I. This is attributed to the greater contribution of the bending modes for I and I* during the photodissociation of i-C3H7I than that of n-C3H7I leading to an enhancement of the nonadiabatic transition between the 3Q0 and 1Q1 states. Additionally, the 3Q0←X transition is not a completely parallel transition for both molecules and the angle between the transition dipole moment and the bond axis is estimated to be about 15° for n-C3H7I and 18° for i-C3H7I, respectively.

Key words: Photodissociation dynamics, n-C3H7I, i-C3H7I, Ion imaging

MSC2000: 

  • O644