O isotope effects and vibration-rotation lines of interstitial oxygen in germanium

Abstract

The infrared absorption of interstitial 17 O and 18 O has been measured at high resolution in natural germanium in a multireflection geometry. The asymmetric mode of 18 O is observed to be broadened by interaction with the phonon background while that of 17 O is unaffected. The broadening is confirmed by results on an 18 O-enriched sample. All the O and Ge isotope shifts can be fitted or predicted rather accurately by a twoparameter semiempirical model using values determined by Pajot and Clauws in 1988. In the multireflection geometry, new lines of low intensity are also observed and they are ascribed to transitions with change of the rotational state of 16 O between the ground and excited vibrational states. Energies of the two-dimensional 16 O rotator are derived from these measurements, with a Ge isotope effect much smaller than the one deduced from phonon spectroscopy.

Fullerene Quantum Gyroscope

“…The classical example is crystalline hydrogen, whose rotational Raman spectrum at temperatures below the melting point of 13 K reveals twodimensional quasi-undistorted hydrogen rotation [8]. Quasi-2D states of a plane rotor were found for H 2 in intercalated graphite [9], on a stepped copper surface [10], and for interstitial atomic oxygen in germanium [11]. Rotational lines of C 2 were only observed in the gas phase as structures accompanying electronic transitions in hot carbon plasma [12 -14].…”

Interacting quantum rotors in oxygen-doped germanium

“…11 The energy spectra deduced from these measurements can be accurately reproduced by a quantum rotor model. [13][14][15] Each rotating Ge 2 O unit within this model is mapped onto a quantum rigid rotor rotating in a two-dimensional plane that is perpendicular to the Ge-Ge axis.…”

Decay mechanism of theν3865 cm−1vibration of oxygen in crystalline germanium

“…Consequently, we might expect them both to decay into three lattice modes, as was assumed initially. 4,5 However, subsequent work established that in Si of natural isotopic abundance, the primary decay channel of the 3 mode is into two phonons. 6 One phonon is the symmetric 1 local mode of the Si-O-Si complex, with an energy of 612 cm −1 , in which the O atom is static and the two Si atoms vibrate in antiphase.…”

“…13 The frequencies of the 3 modes for these two structures are, respectively, 863.9 and 861.4 cm −1 . 5 If the 3 mode decays into three lattice modes, we need to compare these values to the three-phonon density of states. The three-phonon density of states is shown in Fig.…”