Diffraction theory of the impulse mirage effect

Continuous-wave photothermal deflection spectroscopy with fundamental and harmonic responses

“…From Eqs. (5)- (9), we see that the second-order harmonic is proportional to ͑z 1 z D 1 z 1 2 1 z c 2 ͒͑͞z D z c ͒. The last terms in Eqs.…”

“…Recently, Power and co-workers also employed the diffraction theory to study the impulse mirage effect with a one-dimensional temperature field. 9,10 As reported in this Letter, the fundamental and harmonic responses of cw PD signals were studied with Fresnel diffraction theory. We f ind that the centroid moment of the probe beam can provide a rigorous measure of the mirage effect, which leads to a set of meaningful, easy-to-use closed-form analytical solutions for the fundamental and harmonic responses of the PD signal.…”

Beam Deflection Photothermal Spectroscopy

“…v t also becomes invariant to cell-detector distance when the detector is placed in the far field. 7 At low pump beam power, the peak normalized bicell signal, N v t becomes invariant with I 0 . N v t is also invariant to the pump beam radius, !…”

“…5-10% root mean square (RMS) of full scale 20 are typical. Recent work 7 has shown that for impulse n-PDS diffraction is significant when a 0 /! 0 Ä 0.2.…”

Pulsed photothermal deflection with a top-hat beam excitation

“…[11][12][13][14][15][16][17] While the geometric optics approximation is in general sufficiently accurate for most Gaussian beam PTD experiments, it is no longer appropriate when an infinite temperature gradient is present in the beam path. In this case the geometric optics approximation would fail to describe the PTD signal as the integral in Eq.…”