Acta Phys. -Chim. Sin. ›› 2003, Vol. 19 ›› Issue (09): 875-878.doi: 10.3866/PKU.WHXB20030920

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REMPI Spectrum of Atomic Oxygen O(3PJ″) from Photofragment of NO2

Gao Wen-Bin;Hoger T;Halpern J B;Zacharias H   

  1. Department of Applied Physics, Hangzhou Institute of Electronics and Engineering, Hangzhou 310037; 1Physikalisches Institut, Universitaet Muenster, Wilhelm-Klemm Str.10, 48149 Muenster, BRD; 2Chemistry Department, Howard University, Washington DC 20059, USA
  • Received:2003-01-12 Revised:2003-04-21 Published:2003-09-15
  • Contact: Gao Wen-Bin

Abstract: The ion spectrum of the O(3PJ″) from the photodissociation of NO2 at laser wavelength λ=355 nm (28 169 cm-1) has been investigated using resonance enhanced multiphoton ionization (REMPI) and time of light (TOF) mass spectrometer technique. The spin-orbit fine structure resolved ion spectrum of the atomic oxygen from the two-photon transition of O (2p 3PJ″→3p 3PJ’)is obtained. The ion signal intensity of oxygen as a function of the UV ionization laser energy (λ=226 nm) can be well simulated with cubic proportional curve. It shows, atomic oxygen O(3PJ″) is ionized by (2+1) multiphoton absorption process. The obtained three spin-orbit sublevels branching rations of f1=I(3P1)/I(3P2) and f0=I(3P0)/I(3P2) for O(3PJ″=2, 1, 0) are 0.54±0.09 and 0.20±0.04 respectively which is in good agreement with the statistical distribution of 3P2∶3P1∶3P0=1∶0.6∶0.2 .In lower sample(NO2) pressure the collision-induced energy transfer between atomic oxygen sublevels O(3PJ″=2, 1, 0) can’t occur during photodissociation-ionization time (10-8 s).The population of spin-orbit angular momentum split sublevels O(3PJ″=2, 1, 0) is statistical distribution.

Key words: Dissociation, Resonance enhanced multiphoton ionization (REMPI),  Time of flight (TOF), Ion spectrum