In molecule optics, a matter wave of molecules is manipulated by a molecule-optical component made out of external, typically radiative, fields. The molecule-optical index of refraction, n, for a nonresonant IR laser pulse focused onto a molecular beam can be obtained from the energy conservation and wave properties of molecules. Experimentally measured values of n for benzene and nitric oxide agreed well with the calculated values. Since n depends on the properties of molecules as well as those of the laser field, a molecule prism composed of the focused nonresonant laser field can separate a multi-component molecular beam into several components according to their molecule-optical refractive indices n. We obtained a chromatographic resolution of 0.62 for the spatial separation of a mixture beam of benzene and nitric oxide using a focused Nd:YAG laser pulse as a molecule prism.

The photodissociation of t-C 4 H 9 I has been studied at 277 and 304 nm in a supersonic molecular beam. The fragments (I and t-C 4 H 9 radical) are selectively ionized by resonance-enhanced multiphoton ionization and then projected onto a two-dimensional position-sensitive detector to obtain their translational energy and angular distributions. The energy distribution is found to consist of three components: one Maxwell-Boltzmann and two Gaussian distributions. Their anisotropy parameters range from 0.7 to 1.6 and display a parallel transition characteristic, where the greater the kinetic energy of the component, the stronger its anisotropy. From present and previous work, these three components are interpreted in terms of three independent reaction paths on an excited potential energy surface: (1) the prompt dissociation along the C-I stretching mode for the high-energy component, (2) the repulsive mode along the C-I stretching, coupled with some bending motions for the medium-energy component, and (3) the indirect dissociation, probably due to large contribution of the bending motions for the low-energy component. Relative quantum yields for I( 2 P 3/2 ) at 277 and 304 nm have been determined and found to be 0.93 ( 0.03 and 0.92 ( 0.04, respectively. Experiments have shown that t-C 4 H 9 I has the highest curve-crossing probability from the 3 Q 0 to 1 Q 1 state among low-carbon alkyl iodides. The extensive vibrational coupling between two states in the proximity of a crossing point supports this interpretation.

A molecular lens of the nonresonant dipole force formed by focusing a nanosecond IR laser pulse has been applied to benzene and CS 2 molecular beams. Using the velocity map imaging technique for molecular ray tracing, characteristic molecular lens parameters including the focal length ͑f ͒, minimum beam width ͑W͒, and distance to the minimum beam width position ͑D͒ were determined. The laser intensity dependence of the observed lens parameters was in good agreement with theoretical predictions. W was independent of the laser peak intensity (I 0 ), whereas f and D varied linearly with 1/I 0 . The differences in lens parameters between the molecular species were well correlated with the polarizability per mass values of the molecules. A high chromatographic resolution of Rsϭ0.84 was achieved between the images of benzene molecular beams undeflected and deflected by the lens. The possibilities for a new type of chromatography are discussed.

A cylindrical molecular lens is formed by focusing a nanosecond IR laser pulse. Trajectories of a CS 2 molecular beam deflected by the lens are traced using the velocity map imaging technique. The characteristic lens parameters including the focal length, minimum beam width, and distance to the minimum-width position are determined. The laser intensity dependence of the parameters is in good agreement with theoretical predictions. Exciting possibilities for molecular optics and a new type of optical chromatography are opened up.

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