OPTICAL SECOND HARMONIC SPECTROSCOPY OF THE ANATASE TiO2(101) FACE

2001 ◽  
Vol 15 (28n30) ◽  
pp. 3873-3876 ◽  
Author(s):  
G. MIZUTANI ◽  
N. ISHIBASHI ◽  
S. NAKAMURA ◽  
T. SEKIYA ◽  
S. KURITA
Keyword(s):  
Band Gap ◽  
Previous Analysis ◽  
Second Harmonic ◽  
Anatase Tio2 ◽  
Phonon Energy ◽  
Sharp Rise ◽  
Sum Frequency ◽  
Bulk Band ◽  
Frequency Intensity

We have investigated electronic levels of the H 2 O /anatase TiO 2 (101) interface by optical second harmonic spectroscopy. We see a sharp rise of SH intensity above the SH phonon energy 2ℏω~3.6 eV . According to our previous analysis, the SH signal from this face originates mainly from the H 2 O/TiO 2 (101) interface. The sum frequency intensity also shows a rise at ℏω1+ℏω2~3.6 eV . Thus the observed sharp rise of the SH intensity is due to a resonance of an interface band gap at 3.6eV. The energy of this interface band gap is larger than that of the bulk band gap, 3.2eV.

OPTICAL NONLINEARITY VIA PHONONS AS AN INTERMEDIARY

2001 ◽  
Vol 10 (01) ◽  
pp. 65-77 ◽  
Author(s):  
OU FA ◽  
HE MINGGAO ◽  
WU FUGEN
Keyword(s):  
Second Harmonic ◽  
Optical Nonlinearity ◽  
Photon Absorption ◽  
Saturation Phenomenon ◽  
Sum Frequency ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Threshold Phenomenon ◽  
Anti Stokes ◽  
The Given

A new model to describe the origin of optical nonlinearity is presented. In this model, the interaction between light and medium is reduced to the coupling of photons with phonons, which occurs in the crystal lattice vibrating anharmonically. Then the optical nonlinearity originates from the nonlinear photon–phonon coupling or the interaction among phonons themselves. In this paper, more attention is drawn to the latter. By the given model, (1) degenerate and (2) nondegenerate parametric oscillations, (3) Stokes and (4) anti-Stokes Raman scattering, (5) sum-frequency and (6) second harmonic generation and (7) two-photon absorption are dealt with systematically and quantum-mechanically. The results of theoretical analysis show that the effects (1)–(4) are associated with threshold phenomenon, whereas the effects (5)–(7) with the saturation phenomenon.

Polarization, specific heat, band gap and phonon energy of multiferroic GaV4S8

2022 ◽  
Vol 341 ◽  
pp. 114546
Author(s):  
A.T. Apostolov ◽  
I.N. Apostolova ◽  
J.M. Wesselinowa
Keyword(s):  
Specific Heat ◽  
Band Gap ◽  
Phonon Energy
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