الفهرس 
Classical elasticity theory:
illustrated graphically. Formulation of the problem (Statement of the problem)Only 14 pages are availabe for public view
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Abstract
Photothermal spectroscopy is a group of high sensitivity methods used to measure optical absorption and thermal characteristics of a sample. The basis of Photothermal spectroscopy is a photo-induced change in the thermal state of the sample. Light energy absorbed and not lost by subsequent emission results in sample heating. This heating results in a temperature change as well as changes in thermodynamic parameters of the sample which are related to temperature. Measurements of the temperature, pressure, or density changes that occur due to optical absorption are ultimately the basis for the Photothermal spectroscopic methods. Photothermal spectroscopy has been classified by Ingle and Crouch (1988) as one of several indirect methods for optical absorption analysis. Indirect methods do not measure the transmission of light used to excite the sample directly, but rather measure an effect that optical absorption has on the sample. The term indirect applies to the light measurement, not to the optical absorbance. Photothermal spectroscopy is, in a sense, a more direct measure of optical absorption than optical transmission based spectroscopies. Sample heating is a direct consequence of optical absorption and so Photothermal spectroscopy signals are directly dependent on light absorption. Scattering and reflection losses do not produce Photothermal signals. Subsequently, Photothermal spectroscopy more accurately measures optical absorption in scattering solutions in solids and at interfaces. This aspect makes it particularly attractive for application to surface and solid absorption studies, and studies in scattering media.he high sensitivity of the Photothermal spectroscopy methods has led to applications for analysis of low absorbance samples. Dovichi (1987) reviewed the literature regarding the use of photothermal spectroscopy for chemical analysis. The magnitude of the photothermal spectroscopy signal depends on the specific method used to detect the photothermal effect and on the type of sample being analyzed. Photothermal effect also is a phenomenon associated with electromagnetic radiation. The interaction of electromagnetic radiation with matter causes absorption, emission, and scattering of radiation. Except for emission and scattering, the absorbed electromagnetic energy is converted to heat by various nonradiative processes and induces changes in temperature, pressure, and refractive index of the medium. The discovery of the photothermal effect dates back to Bell’s discovery of the photoacoustic effect in 1880, but it is after the invention of the laser that the photothermal spectroscopies became popular. In 1964, Gordon et al. found a beam divergence effect from liquid samples that were placed in a gas laser cavity. This phenomenon was correctly interpreted in terms of the “thermal lens” effect produced by heating induced by the Gaussian laser beam.Today, Photothermal spectroscopy is widely used in physics, chemistry, biology, and engineering. The Photothermal method has a number of merits compared with other methods. It is highly sensitive and applicable to different types of materials (gas, liquid, liquid crystal, and solid), transparent and opaque. It can be used in vacuum and in air, and with samples of arbitrary shape. Radiation of any wavelength can be used (radio frequency, microwave, IR, visible, UV, and X-ray, etc.). It is produced by the photo-excitation of material, resulting in.