Abstract

Hydrogen bonds are ubiquitous in nature. It is hardly surprising, therefore, that since their discovery over 70 years ago hydrogen bonds have aroused tremendous interest. The most direct route to the analysis of these bonds involves detection of their vibrational modes which occur in the far-infrared, a region long referred to as the gap in the electromagnetic spectrum. Indeed, unlike techniques at both longer and shorter wavelengths, tunable far-infrared spectroscopy is a very recent development. Previous work in this region was performed with line tunable lasers coupled with eigenstate tuning through the application of large electric or magnetic fields. The resulting resonance spectra are quite complicated, the coverage is poor, and the necessity of predicting zero-field constants from high-field data often renders the observed transitions unassignable. Add to these difficulties the problem of simply producing sufficient quantities of the weakly bound clusters for spectroscopic study, and it is easy to see why our knowledge of such systems is so limited.

© 1988 Optical Society of America