Fast beam experiments using laser

Fast beam experiments using laser excitation 

The problems associated with radiative cascade in beam- 

Similar experiments liave been performed on ion beams which have been excited by passing through gas target cells and which are then re-excited by a tunable dye laser. An accuracy of 1 part in lO seems to be attainable with this new technique and many more results will appear in the near future. 

The delayed-aoincidenoe method using electron excitation 

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Fast beam experiments using laser excitation... 

Classical saturated absorption experiments on fast beams require different laser wavelengths to saturate and probe the same transition. However, a three-level system in V or A configuration can be realized to use the same direct and retroreflected laser beam interacting with the velocity class p under the condition... 

While one might expect that the techniques developed for photodissociation studies of closed-shell molecules would be readily adaptable to free radicals, this is not the case. A successful photodissociation experiment often requires a very clean source for the radical of interest in order to minimize background problems associated with photodissociating other species in the experiment. Thus, molecular beam photofragment translation spectroscopy, which has been applied to innumerable closed-shell species, has been used successfully on only a handful of free radicals. With this problem in mind, we have developed a conceptually different experiment [4] in which a fast beam of radicals is generated by laser photodetachment of mass-selected negative ions. The radicals are photodissociated with a second laser, and the fragments are detected in coinci-... 

The need for accurate computational procedures to evaluate detailed properties of gas phase chemical reactions is evident when one considers the wealth of information provided by laser, molecular beam and fast flow experiments. By stressing ordinary scalar computers to their limiting performance quantum chemistry codes can already provide sufflciently accurate estimates of the stability of several small molecules and of the reactivity of a few elementary processes. However, the accurate characterization of a reactive process, even for small systems, is so demanding in terms of computer resources to make the use of supercomputers having vector and parallel features unavoidable. 

Using a laser operating on 14C1602, the regular band of which spans 12.0 pm, it is possible to perform the experiment with a transverse geometry with a fast ion beam, or with a slower ion beam, for example from an ECR ion source. A possible setup is outlined in fig. 6. Because of the shorter interaction time, a build-up... 

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