One-photon dissociation

Velocity mapping has been employed in studies of 02 photophysics taking place at the one-photon [64,65], two-photon [66], and higher photon [24,25] levels. A short summary of the studies of one-photon dissociation that illustrates the importance of three-vector correlation measurements in photofragmentation of molecular oxygen will be given. Processes resulting from absorption of three or more photons will be described in more detail here since they have aspects in common with the D2 studies. 

We consider now the case of dissociation by the net absorption of just one photon, to jjje1 termed one-photon dissociation. As in the weak-field domain (Chapter 3) the (molecule is assumed to dissociate into two fragments as a result of the interaction (with a laser pulse. It is convenient to parametrize the incident electric field [Eq. (1.35) as... 

Laser-induced fluorescence photofragment spectroscopy studies with state-selective interfragment recoil measurement have not been performed to any appreciable extent. A preliminary kind of experiment has recently been carried out in an MPD case by using the time-of-flight technique under bulk condition and with rather limited spectral resolution. A Doppler spectroscopy study has been carried out in a one-photon dissociation case where electronically excited fragments were produced under bulk condition, and linewidth measurement was made in emission interferomet-rically. A first experiment with tunable LIF detection has been made recently by McDonald et al., who dissociated HN3 at 266 nm and... 

Here we report Doppler experiments carried out recently in our laboratory. Two kinds of studies have been made, both with the main objective to establish and investigate the potential of the method (1) first multiple-photon dissociation Doppler experiments under crossed-beam condition with CjHjCN and CH3NH2, and (2) first linewidth measurement in single vibrational-rotational levels of NO produced by one-photon dissociation of NO2 in bulk with unpolarized and polarized light, in connection with complete internal energy distribution measurements of the NO fragment. 

Fig. 6.17. One photon dissociation spectrum of the 2,4-hexadiyne-cation isomer of CeH in the Basel 22-pole ion trap. In the upper panel, the vibrational and rotational degrees of freedom of the ions were cooled to 30 K in collisions with helium. Comparison with the 300 K spectrum (lower panel) reveals that the origin band at 486 nm becomes very narrow and that there is no evidence of hot bands. For more details see Ref. 59.

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