Persistent Infrared Spectral Hole Burning of NO(-2) Ions in Potassium HalideCrystals. 1. Principle and Satellite Hole Generation

摘要

New features are resolved within the internal vibrational mode spectra of NO2defects in KCl, KBr, and KI crystals at low temperatures using high-resolution Fourier transform spectroscopy and persistent infrared spectral hole (PIRSH) burning separately and together. With interferometry it has been discovered that the vibrational linewidths of the different modes range over a factor of 300-from 0.01 cm(-1) to approximately 3 cm(-1) and, with PIRSH burning, it has been demonstrated that the narrowest lines are inhomogeneously broadened while the broadest ones are homogeneously broadened. PIRSH's have been found in some internal modes and combination bands of the N02 molecule when pumped with low-intensity single lead salt diode lasers; however, detectable persistent holes are not produced in all of the modes because of a competition between hole production and relaxation by tunneling at low temperatures. This competition results in a hole burning intensity, below which hole relaxation overwhelms hole production and only small holes may be produced. The most unusually shaped absorption features are the V-shaped notches in the reorientational tunneling fine structure at the NO(2-) bending mode frequency in KCl and KBr. Of all the internal modes that do show pronounced PIRSH burning, these V-notched absorption bands exhibit the most striking behavior. Multiple satellite PIRSH's are detected at frequencies away from the single laser burn frequency with a broadband probe beam produced by a high-resolution Fourier transform interferometer. An explanation for these satellite holes is derived from temperature, plastic deformation, and uniaxial stress dependence measurements on the KCl:NO(2-) absorption spectrum.