Raman scattering of light by 2LO-phonons

The analysis of the two‐phonon resonant hyper‐Raman effect

“…Because of this, it needs to consider also the RHRS induced by the two-photon transitions in s-excitonic states which can occur owing to the weakly-forbidden transitions or by virtue of the participation of the higher-lying conduction bands and the deeper valence bands [7]. This two-phonon RHRS process is similar to the second-order RRS theoretically investigated by us earlier [4] and differs from the RRS by the two-photon transition to a s-exciton state. The cross section for such a two-phonon RHRS was derived by us earlier [9].…”

“…However, the analysis of the RRS by 2LO phonons has in particular shown that the forbidden transitions between s-excitons should be not disregarded if the effective masses of electrons and holes considerably differ [4]. If the transitions between s-and p-excitons are taken into account only, the state 4 λ can be solely a p-exciton. were theoretically investigated and their matrix elements were obtained in works devoted to the twophoton absorption [6,7].…”

“…Because the RHRS is considered for the doubled energy of exciting radiation below the 2P exciton level, the Green's function approach used in the theory of two-photon absorption [6,7] can be applied in calculations of the sums over 4 λ and 2 λ . The corresponding relations were derived by us earlier [4,8].…”

Two-phonon resonant hyper-Raman scattering treatment in a CdS crystal

“…It is known that the matrix element between s-and pexciton states is weakly dependent on the phonon wave vector, q, for qa 1 whereas J 0 (qa, κ S , n) ∝ q [16][17] However, it should be noted that the HRS induced by two-photon transition to a s-exciton is involved in a scattering process if the selection rules allow [20]. Our estimations performed for the one-phonon HRS have shown that its contribution to the hyper-Raman intensity can be appreciable in resonant conditions [20].…”

“…We note that J l (Q, κ S , n) was obtained by us in [16] and is defined by the expression (27). Owing to a smallness of q L and q S , we ignore the photon wavevectors in the denominator of Eq.…”