Analysis of the repetitively pulsed dual-beam thermo-optical absorption spectrometer

Abstract

An analysis is presented for the repetitively pulsed dual-beam thermo-optical absorption spectrometer, which has been used recently to determine the absorption strengths of several organic liquids in the visible spectral region covered by the cw tunable dye laser. The model succeeds in describing the development of the thermal lens on a pulse-by-pulse basis. The equations derived are then used to optimize the spectrometer design with respect to the parameters which are under the control of the experimenter. It is further demonstrated how one identifies the region of linear operation of the spectrometer. Finally, it is shown how the relative absorptivities of compounds may be determined.

Probing Intermolecular Interaction through Thermal-Lens Spectroscopy

“…The S(m) part can be attributed to the molecular contribution of TL resulting from the change of the composition of the binary liquid solutions. So, to extract the molecular property information responsible for the modulation of the TL signal trends, we take the ratio between the TL trends obtained from the experiment and calculated by using the physical parameters only as (10) The results are shown in the Figure 7, which indicates that the trends in the modulation of the TL signal mostly originate from changes in the molecular properties of the binary liquid mixtures as their relative composition changes. A closer inspection of Figure 7 also indicates that the signature of the molecular properties of the individual binary liquid components is effectively reflected and is dominant at the two end points of the x-axis, when the volume fraction of the solute (in our case methanol) is approaching 0 or 1.…”

“…This single-beam TL technique was improved vastly with the introduction of a dual-beam version. 10 Subsequently, many authors used two-color Z-scan techniques and pump-probe experiments to measure TL in different samples. [11][12][13][14] TL spectroscopy is often the preferred analytical tool, particularly for molecular systems with strong absorbance in comparison to fluorescence.…”

Vibrational relaxation study of O3 in rare gas and nitrogen matrices by time resolved infrared–infrared double resonance spectroscopy

“…It probably corresponds to a change induced in the refractive index of the probed solid, as heat flows through it, producing a deviation of the probe beam path. 34 It can also be related to the well-known thermal lens effect in laser theory. 35 By moving the pump spot, one can change the amplitude and the sign of this long component of the DR signals, and it can even be eliminated by a proper adjustment of the relative positions of the impacts.…”

Measurement constraints in laser based thermal lens experiments

“…TLS has passed through a number of developmental stages [12][13][14][15][16]. In dual beam experiments, one beam acts as a pump beam while the other beam acts as a probe beam.…”