Raman Effect in Cuprous Oxide Compared with Infrared Absorption

Abstract

A complex Raman spectrum of Cu2O has been measured using the Kr laser line at 6471 Å, and comparison with the infrared absorption spectrum is made. An F2g Raman active phonon, postulated from symmetry considerations and infrared absorption measurements to lie at either 606 or 181 cm−1, could not be observed. Strong lines are, however, observed at 220, 204, and 192 cm−1.

On a biphononic origin of the 1125 cm−1 absorption band in cuprous oxide

“…The general features of the IR reflectance spectrum of Cu 2 O have been published by several authors [15,16]. It is well established that there are two allowed IR active phonons of F 1u symmetry with TO phonon frequencies ω T O1 ≃ 150 cm −1 and ω T O2 ≃ 605 cm −1 .…”

Resonance Raman Scattering at the Forbidden Yellow Exciton inCu2O

“…6 ' 14 The assignment to the T 25 + mode is not compatible with polarization studies. 9 Our observation that the Raman cross section is essentially independent of sample preparation suggests that defects are not important. The two-phonon assignment yields a consistent explanation and good agreement between theory and the experiment.…”

Luminescence ofCu2O-Excitonic Molecules, or Not?

“…This character- istic asymmetric broadening indicates that these peaks must originate from phonon-assisted recombination of a free exciton. 14 From the earlier work on infrared absoprtion 7 ' 8 ' 10 ' 12 ' 13 ' 15 and Raman scattering in C^O, 10 * 11 ' 13 we are able to identify these various peaks as due to decay of the n = l yellow exciton with simultaneous emission of a phonon or phonons as listed in Table I. The assignment is partially based on the theoretical calculation of Carabatos and Prevot.…”

“…12 a 0 contains T" X/ % and so OQVT Is temperature independent. 13 Small uncertainties in T 0 produce relatively large uncertainties in a 0 . 14 Luminescence spectra of Cu 2 0 excited at various temperatures by a tunable dye laser showed no evidence of the existence of excitonic molecules (or biexcitons) as suggested recently by Gross and Kreingol'd.…”