Thermal effects in photothermal spectroscopy and photothermal imaging

Abstract

The effect of thermal parameters on photothermal spectroscopy and photothermal imaging for certain types of spatially heterogeneous samples has been studied. Results have been obtained for both photoacoustic and photothermal deflection modes of detection. Specific attention has been paid to optical saturation in samples whose properties exhibit gradual spatial changes and to the dependence of the photothermal signal on the individual thermal parameters. Most photothermal spectroscopy has been done using thermally homogeneous samples, and most photothermal imaging using optically saturated samples. In this paper, these limitations are relaxed, and the photothermal signal is assumed to depend simultaneously on gradual spatial variations in the optical absorption coefficient, thermal conductivity, and thermal capacity of the sample.

Application of photothermal deflection spectroscopy to electrochemical interfaces

“…Other solutions can be found in the photoacoustic spectroscopy (PAS) and photothermal spectroscopy (PTS) literature [13,50].…”

“…The original application was for homogeneous phases followed by extension to interfacial spectroscopy [12][13][14][15].…”

“…The current trace contains two anodic peaks, AI and All. These represent the [1][2][3][4][5][6][7][8][9][10][11][12][13] The DC deflection detects the concentration gradients. The deflection marked X is an interesting feature.…”

“…The deflection that the LPD measures is the sum of the deflections of all the differential ribbons (weighted by power). [2][3][4][5][6][7][8][9][10][11][12][13][14] The linear power density of each planar slice, P'(x), is obtained by integration of Equation 2-11 in the y direction. The gradient, em/ ax , is then calculated using Equation 2-10.…”

“…S(t} = Asin(cot+(/)) [2][3][4][5][6][7][8][9][10][11][12][13][14][15] A lockin would typically measure the root-mean-square amplitude.l Peak-topeak amplitude is another common measure. The different measures are directly proportional to each other:…”