The photodissociation of oxalyl. chloride, (ClC0)2, has been studied near 23.5nm using the photofragment imaging technique. Observed products include both ground state Cl e P 3 ; 2) and spin-orbit excited Cl* (2 P 1 ; 2) chlorine atoms and ground electronic state CO molecules.-The rotational distribution obtained for the CO v=O product is peaked at about J =30 and extends be-•

The OH(v@ \ 4, N@ \ 1) products of the photon-initiated reaction O(1D 2 ) N@) ] H have been probed using Doppler-resolved ] H 2 (v \ 0) ] OH(v@, laser induced Ñuorescence. The data are used to extract the product stateresolved di †erential cross-section and excitation function. The state-speciÐc angular distribution displays pronounced forwardÈbackward peaks with a bias for backward scattering. The experimental data are compared with the results of QCT calculations, using two alternative ab initio versions of the ground 11A@ potential energy surface, and a recent ab initio version of the Ðrst excited 11AA potential energy surface, in order to assess its possible inÑuence on the overall dynamics of the reaction.

Relative ionization cross sections have been determined for the production of the molecular ion CH3Cl+ and the fragmentation product CH+3 from the 200 eV electron impact ionization of spatially oriented CH3Cl molecules in a cross beam experiment. The ionization cross section for CH3Cl+ formation is higher at the positive end, or CH3 end, of the molecule while the cross section for formation of the CH+3 fragmentation product is independent of spatial orientation, within experimental uncertainty.

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The attenuation of hexapole-focused CH3Cl molecular beams has been studied as a function of inert gas and nitrogen gas pressure in a hexapole-collision cell. Cross sections have been determined as a function of relative velocity, using seeded beams, and as a function of specific |JKM〉 states through variation of the electric field strength in the hexapole. Beam attenuation is attributed to rotationally inelastic collisions in which a beam molecule following a focusing upper Stark state (KM < 0) trajectory through the hexapole field is converted by a ΔM or ΔJ, ΔM transition into a nonfocusing rotational state (KM = 0 or KM > 0), which then follows a modified, nonfocusing trajectory and is lost from the beam. Experimental cross sections are in the range from 200 to 670 Å2, consistent with collisions controlled by a long-range interaction (8 to 15 Å) involving the transfer of a few J mol-1 of energy. Collision cross sections estimated using a van der Waals interaction potential with dispersion and dipole−induced dipole terms suggest that cross sections of these magnitudes most probably correspond to collisions in which only the M quantum number changes.