DFG difference frequency

Abbreviations AAS, atomic absorption spectroscopy AES, Auger electron spectroscopy AFM, atomic force microscopy BE, binding energy DFG, difference frequency generation DFT, density functional theory EBL, electron beam lithography EELS, electron energy loss spectroscopy ETEM, environmental transmission electron microscopy fee, face-centered cubic FEM/FIM, fleld emission... 

DFG difference frequency generation ICSU International Council of the Scientific... 

This shows that there are now oscillating dipoles at frequencies (coi + CO2) and (cOi — CO2), which give rise to SFG and difference frequency generation (DFG), respectively. When C0i = C02, Eq. (5.7) becomes ... 

Another relatively new technique is the infrared visible sum frequency generation (SFG) spectroscopy and the difference frequency generation (DFG) spectroscopy [13], both of which represent vibrational spectroscopic techniques sensitive only to the material located at interfaces. 

When the incoming field E consists of two frequencies, O) and dipoles non-linearly oscillating at frequencies (o) + (o ) and (o) - (o ) are Induced as well. In the sum-frequency generation (SFG) technique one focusses on the output at frequency + co and in the difference-frequency generation (DFG) technique on - a) ). As is the case with SHG, SFG and DFG are electric dipole-forbidden in centrosymmetric media. 

Certain crystals (those in which the unit cell lacks inversion symmetry) enable a variety of useful three-wave mixing processes Second Harmonic Generation (SHG), u>3 = uq + uq Sum Frequency Generation (SFG), uz = uq + w2 Difference Frequency Generation (DFG), u>z — uq — w2 and Optical Parametric Oscillation (OPO), uq = uq + W3. In SHG, for example, energy and momentum (wavevector) conservation requires, for colinear propagation,... 

One method developed to minimize the contribution of /nr to the nonlinear spectrum is the Difference Frequency Generation (DFG) approach [13]. Since /nr is dependent on the electronic states of the metal, shifting the output frequency to lower energy avoids exciting the resonance modes in the metal. Although DFG signal is susceptible to contributions of fluorescence from the sample, it has been shown to help in the analysis of electrochemical interfaces [22]. 

Sum and difference frequency generation at electrode suifaces [130] The investigation of vibrational and electronic properties of the electrochemical interface by using nonlinear optical techniques of visible-infrared sum (SFG) and difference (DFG) frequency generation constitutes an interesting aspect of the study of adsorbed species. The vibrational behavior of H-Pt(hkl) system, both in the underpotential and overpotential regime, adsorption of CN on Au(hkl) electrode (using DFG), electrode surface electronic properties were studied and measurements of the PZC were carried out [131]. 

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