Detection mirage

The technique employed is IR-FT photothermal beam deflection spectroscopy (PBDS). It is an off-shoot of photoacoustic spectroscopy (PAS) [1] and is based on the "mirage detection of the photothermal effect invented by Boccara et al. [2] and shown to result in a spectroscopic technique of remarkable versatility and utility. Some applications of "mirage spectroscopy," mainly in the visible, and theoretical treatments, have been described [3 6]. The method has now been developed for use in the IR. The spectrometer and techniques are described in detail elsewhere [7], but it will be useful to give a brief outline of the principles. 

Photothermal deflection spectroscopy — Photothermal deflection is a photothermal spectroscopic technique used to detect the changes in the refractive index of the fluid above an illuminated sample by the deflection of a laser beam. There are two sources from which the thermal deflection effect might appear. One of them is produced by a gradient in the refractive index after a thermal excitation where the density also varies with temperature, in the so-called mirage effect. And the other one is produced by the topographical deformation of the surface over which the laser beam is reflected. This effect is known as photothermo-elastic effect or surface photothermal deflection [i]. 

An alternative technique is the so-called Photothermal Beam Deflection Spectroscopy [PBDS], based on the so-called mirage effect first reported by Boccarra and coworkers [39, 40]. In this case, the periodic temperature rise caused by the absorption of the modulated IR radiation (i.e. the photothermal effect) is detected optically because it causes periodic deflections of a laser beam passing close to the surface of the solid sample. The PBDS technique has some advantages over the PAS technique, because of its lower Hmits of sample dimensions, but it has disadvantages because of the critical geometric setup. Like PAS, PBDS can have advantages with respect to traditional IR technique for the detection of surface... 

The corrals exhibit standing-wave patterns of electrons, and the first idea was to use the corrals to study quantum chaos [169, 170, 171, 172]. Unfortunately, the walls leaked too much for the electrons to bounce around long enough to detect any chaotic effects [173]. In 2000, Manoharan et a 1. [174] performed an experiment on an elliptic quantum corral, where a quantum mirage of a Co atom at one of the focus points of the ellipse was seen when a Co atom was placed at the other... 

Plichon V, Besbes S (1990) Mirage detection of counter-ion flux between Prussian blue films and electrolyte solutions. J Electroanal Chem 284 141-153... 

Salazar, A., Sanchez-Lavega, A., Fernandez, J., 1993. Thermal diffusivity measurements on solids using coUinear mirage detection. J. Appl. Phys. 74 (3), 1539-1547. 

Refractive index changes in a quiescent electrolyte produced by an electrochemical reaction at a working elec-trode/solution interface can be detected either interfero-metrically [123] or by probe beam deflection (PBD) [148]. The mirage deflection is due to both a tempera-... 

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