STATE-SPECIFIC NEUTRAL TIME-OF-FLIGHT OF CO FROM KETENE PHOTODISSOCIATION AT 351 NM - THE INTERNAL ENERGY-DISTRIBUTION OF CH2((X)OVER-TILDE(3)B(1))

Metastable lime-of-flight (TOF) spectroscopy was used to measure the t ranslational energy distribution of specific rotational states of CO f ormed from ketene photodissociation (CH2CO-->CH2+CO) at 351 nm. This d istribution could be directly related to the internal energy distribut ion of the other fragment ((X) over tilde B-3(1) CH2) formed in the re action, thereby giving a correlated distribution of the internal state s of the fragments. This technique overcomes the spectral complexity a ssociated with detection the <(X)over tilde B-3(1)> state CH2. Previou s measurements of the CO rotational distribution were simulated theore tically using the impulsive model and zero-point vibrational energy co nsiderations. These models predicted that the rotational distributions of CO and CH2 should be uncorrelated, that similar to 10% of the CH2 should be vibrationally excited with one quantum in the bending mode, and that the rotational energy distribution of CH2 should peak near ze ro. Measurements presented in this paper show a slight anticorrelation of CO and CH2 rotations, no vibrational excitation of CH2 and Gaussia n-like rotational energy distributions of CH2 that peak at similar to 1 kcal/mole and have a full width at half-maximum of similar to 0.8 kc al/mol. Qualitative explanations for this behavior are presented. (C) 1996 American Institute of Physics.