The Angular Dependences of Two‐Photon Transitions to Surface States

Abstract

The Angular Dependences of Two-Photon Transitions to Surface States A.I. BOBRYSHEVA, S.A. MOGKALENKO, andV.T. ZYUKOV BYThe angular dependences of two-photon absorption intensities of polarized beams due to allowed transitions from the totally symmetric ground state of an insulating crystal to excited surface states have been calculated. Any of the sutface states is characterized by an irreducible representation of ten two-periodical point groups. The case is considered when the top of the valence band and the minimum of the conduction band is at the centre of the Brillouin zone and direct band-to-band dipole transitions take place at this point. These angular dependences hold for band-to-band, exciton, and biexciton transitions.Recently surface excitons have been detected in GaAs /l/, Si /2/, ZnO /3/ by means of photoemission spectroscopy. Additional information about properties of surface excitons can be obtained by conventional optical methods / 4 / .On the ground of group-theoretical analysis the polarization dependence of the absorption coefficient due to one-photon transitions to surface states located on the (111) plane of Si was established /5/.

The one‐ and two‐photon absorption due to surface state excitons

“…The two-photon transitions take place from the ground state of the crystal to the surface state excitons with quantum numbers n 2 Iml, Iml = 1 in t,he allowed case and to the states with quantum numbers n = m = 0, and n 2 Iml ; Iml = 2 in the forbidden case. The dependences upon the polarization angle of photons are obtained and they agree with angular dependences obtained in [9]. We derive also the ratios of the oscillator strengths of two-and one-photon transitions.…”

“…respectively [9]. The probabilities of two-photon transitions to these states depend in different ways upon the polarization directions of two photon beanis.…”

Optical Properties of Biexcitons in ZnSe/Zn1−xMnxSe Quantum Wells

“…The angular dependences of the probabilities of two-photon transition from the ground state of an insulating crystal to excited two-dimensional electronic states characterized by an irreducible representation of the two-periodical point groups have been calculated in [9] and of 32 three-periodical point groups in [12]. It can be expected that two-photon absorption polarization experiments will be useful to distinguish between two-dimensional and three-dimensional states.…”