Electronic spectral parameters and IR nonlinear optical features of novel Ag0.5Pb1.75GeS4 crystal

In this paper, we report on novel Ag0.5Pb1.75GeS4 single crystals grown by the Bridgman–Stockbarger method. For these crystals we have performed X-ray photoelectron spectroscopy (XPS) studies of the valence-band and core-level electron states. Second harmonic generation efficiency of Ag0.5Pb1.75GeS4 powder samples by using CO2 laser light depending on the power density up to 1100MW/cm2 has been obtained within the temperature range 77–520K. The obtained dependences indicate relatively strong enhancement of photoinduced SHG output efficiencies as temperature increases. Both the spectra taken at ambient and 520K temperatures have shown similar behavior—rapid growth to saturated values of SHG efficiency with an increase of fundamental beam power density up to 400MW/cm2, then slowly decreasing with power density reaching a value of 800MW/cm2 and finally these features show a second small maximum at a fundamental beam power density equal to 900MW/cm2. Beyond this power density both SHG values start to decrease. ► Novel Ag0.5Pb1.75GeS4 crystals were synthesized. ► A dramatic decrease of the relative intensity of the XPS C 1s core-level spectrum of the crystal surface after Ar+ ion-bombardment was found. ► Strong enhancement of photoinduced SHG output efficiencies with temperature increment is observed.