PHOFEX Spectra of Ketene

An experimental setup identical to that for PHOFEX spectra can be used to measure correlations between two scalar (internal state population, kinetic energy) quantities or between a scalar and a vector quantity (angular distribution of fragment rotation J or velocity v). By holding the PROBE laser frequency fixed and scanning the MONITOR laser through the Doppler pro- 

Most diatomic molecules are refractory, reactive, and heavy. Some are so fragile that room temperature collisions would destroy them. Molecules that dissoci- 

Molecule sources may be divided into three types thermal, supersonic jet, and cold collisions. Thermal sources (King furnace King, 1926 Broida oven West, et al, 1975 electric or microwave discharge Fehsenfeld, et al., 1965 static gas cell) are simple, convenient, and versatile. However, when the rotational partition function, kT/B, approaches 103, each vibrational band will contain many hundreds of rotational lines, the spectrum will become congested, vibrational bands will overlap each other, and analysis will be difficult. 

A photolysis jet (Monts, et al., 1980) works by introducing a polyatomic parent molecule into the photolysis region just behind the jet orifice. After photolysis, the normally extremely reactive photolysis products are swept through the expansion region so quickly that their only collision partners are inert gas atoms. 

In a pyrolysis jet, (Chen, et al., 1986 Dunlop, et al., 1988 and 1989) parent molecules are swept quickly through a very high temperature region just before exiting the jet. There is an art to the selection of a parent molecule optimal for production of the desired pyrolysis fragment (Chen, et al., 1986). In a pyrolysis source, the weakest bond breaks first and subsequent reactive collisions are minimized. 

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