Spectroscopy intermodulated

The reaction of elemental phosphorus with hydrogen was also used for PH2 production. H atoms from MW-discharged H2 were passed over the red modification, and the resulting PH2 was detected by LIF [51, 52], IMF (intermodulated fluorescence) [27], or MW spectroscopy [14]. The reaction of phosphorus vapor with atomic or molecular hydrogen did not lead to any PH2 electronic emission [18]. Emission bands, which had been observed during the reaction of elemental P with atomic H, were first attributed to PH2 [53,54], but they were later shown to be due to HPO [55]. 

Fig. 2.13 Intermodulated fluorescence method for saturation spectroscopy at small densities of the sample molecules (a) experimental arrangement (b) hyperfine spectrum of the v" = 1,...

The sensitivity is 2-3 orders of magnitude larger than that of saturation spectroscopy. It is surpassed only by that of the intermodulated fluorescence technique at very low sample pressures (Sect. 2.3.1). 

A noise and nonlinearity of thin and thick film resistors are used as rehabUity indicators to make a prediction of resistor rehabdity. The resistor noise is proportional to the current density and this property makes it a valuable characteristic for detecting imperfections and abnormaUties. The properties of thick fdm conducting layers were analyzed by Electro-Ultrasonic Spectroscopy. It is shown that intermodulation component is more sensitive to defects in resistors than non-linearity index NLL... 

M.S. Sorem and A.L. Schawlow, Saturation Spectroscopy in molecular iodine by intermodulated fluorescence, Opt. Common. 5 148 (1972). 

Both harmonic and electrochemical frequency modulation (EFM) methods take advantage of nonlinearity in the E-I response of electrochemiced interfaces to determine corrosion rate [47-50]. A special application of harmonic methods involves harmonic impedance spectroscopy [5i]. The EFM method uses one or more a-c voltage perturbations in order to extract corrosion rate. The electrochemical frequency modulation method has been described in the literature [47-50] and has recently been reviewed [52]. In the most often used EFM method, a potential perturbation by two sine waves of different frequencies is applied across a corroding metal interface. The E-I behavior of corroding interfaces is typically nonlinear, so that such a potential perturbation in the form of a sine wave at one or more frequencies can result in a current response at the same and at other frequencies. The result of such a potential perturbation is various AC current responses at various frequencies such as zero, harmonic, and intermodulation. The magnitude of these current responses can be used to extract information on the corrosion rate of the electrochemical interface or conversely the reduction-oxidation rate of an interface dominated by redox reactions as well as the Tafel parameters. This is an advantage over LPR and EIS methods, which can provide the Z( ) and, at = 0, the polarization resistance of the corroding interface, but do not uniquely determine Tafel parameters in the same set of data. Separate erqreriments must be used to define Tafel parameters. A special extension of the method involves... 

Fig.9.46. Experimental arrangements for intermodulated fluorescence spectroscopy (left) and intermodulated opto-galvanic spectroscopy (right) [9.178]...

J.E. Lawler, A.L Ferguson, J.E.M. Goldsmith, D.J. Jackson, A.L. Schawlow Doppler-free intermodulated optogalvanic spectroscopy. Phys. Rev. Lett. 42, 1046(1979)... 

Fig. 9.60. Gompaxing recordings of the 5882 A Ne line using POLINEX upper curve) and intermodulated fluorescence spectroscopy [9.374]...

G. -Y. Yan Polarization intermodulated excitation (POLINEX) spectroscopy of helium and neon. Opt. Commim. 37, 87 (1981)... 

Fig. 10.19. OODR spectroscopy in a collimated molecular beam with overlapping pump and probe beam and detection at the sum frequency (intermodulated fluorescence) [10.39]...

Such power levels can be quite adequate for Doppler-free saturation spectroscopy, as demonstrated in a series of recent studies of ultraviolet transitions of neutral helium in our laboratory at Stanford. (35-37) Fig. 5 shows as an example a spectrum of the 2 S - 5 P transition of He near 294.5 nm, recorded by intermodulated fluorescence spectroscopy. The ultraviolet radiation was generated by a yellow cw ring cavity dye laser with cavity-enhanced external ADA (ammonium dihydrogen arsenate) frequency doubler. The absorbing metastable He atoms were produced by electron impact excitation of He gas at about 0.04 torr. The spectrum shows a cluster of resolved line components which could be assigned after the fine and hyperfine Hamiltonian had been diagonalized in an uncoupled representation. We were surprised to learn that the hyperfine structure of the 5 P state of this simple 3-body system had been neither measured nor calculated before. 

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