HIGH-RESOLUTION LASER SPECTROSCOPY OF METHANE CLUSTERS TRAPPED IN SOLID PARAHYDROGEN

Clusters of methane are isolated in solid parahydrogen. The vibrationa l spectral region of the nu(4) fundamental of methane molecule is surv eyed with a Fourier transform infrared spectrometer and a high-resolut ion difference-frequency infrared laser system. More than 200 sharp ab sorption lines are discovered whose linewidth is as narrow as 0.007 cm (-1) (200 MHz). The spectrum indicates that the rovibrational levels o f the clusters of small sizes are well quantized in solid parahydrogen . (C) 1997 American Institute of Physics.