New results concerning the properties of acoustic phonons 0.87 THz in ruby are considered including (1) attenuation and anharmonic scattering of ballistic phonons and (2) kinetics of resonance phonon trapping

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Participation of the 29 cm-1 phonons resonant with the 2 A ¯ − E ¯ interval in the Cr3+ metastable E-state in the excitation energy transfer between the Cr3+ ions in ruby has been discussed repeatedly in the literature[1,2]. The present experiments have been carried out at 1.8 K on Al2O3:0.02% Cr crystals under stationary laser pumping. The inhomogeneously broadened R1 luminescence line reveals weak extended structured wings associated with E ¯ − 4 A 2 transitions in the strongly perturbed Cr3+ ions (Fig.1). Injection into the sample of heat pulses from a heater film deposited on its surface has been found to generate positive luminescence pulses I(t) on the short wavelength wing of the R1 line. These-pulses originate from the phonon induced E ¯ -excitation energy transfer from the main distribution ions (line center) to the perturbed ions.

The paper reports on the observation of an lous nonmonotonic dependence of trapping of the 29 cm-ygEz nons on magnetic field. The effect is due to inelastic phonon scattering processes involving the creation (absorption) of a Zeeman quantum of the %level (resonance spin-flip phonon Raman scattering) /I/.

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