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Microwave detection

Flash photolysis with microwave detection of charge carriers could become an additional technique in the future. The method has not yet been applied to colloids but has been used with small suspended particles. Immediately after the laser flash a conductivity signal was observed which decayed in the 0.1 to 1 microsecond range. The signal was longer-lived for a suspension of TiOj in para-dioxane than in Decalin. Such an effect of the surrounding medium on the decay kinetics of the conductivity indicates that surface states are involved... [Pg.156]

B. D. Quimby, P. C. Uden, R. Barnes, Atmospheric pressure helium microwave detection system for gas chromatography, Anal. Chem., 50 (1978), 2112-2118. [Pg.723]

The preparation of compounds containing nitrogen double bonded to another heteroatom has been accomplished by a rDA pathway. Cis- and (rnns-azomethane have been synthesized from tetrahydropyrida-zine (171) by thermal retrodiene extrusion (equation 77). The anti conformation of (171) is presumed to give (rnns-azomethane and the syn conformations yields the cis-isomer. Preparation of nitrosyl hydride (173) has been accomplished under mild nonphotochemical conditions, unlike conditions used in previous preparations. The extrusion of nitrosyl hydride from anthracene adduct (172) as shown in equation (78), which occurs at a very mild temperature, was followed by microwave detection of (173). [Pg.576]

The microwave-detection method has been developed [141] for the study of ionic species and their reactions in nonpolar liquids on a nanosecond timescale, and relies on the fact that microwaves are attenuated in weakly conducting media. It is very useful, for example, for the study of geminate recombination of radical ions in liquid hydrocarbons. It is also more suitable than either optical or D.C. conductivity methods for the study of homogeneous ion recombination processes where problems in data analysis can arise from underlying absorptions and distortion of the kinetics due to separation of the ions, respectively. [Pg.621]

The only yttrium compound of commercial interest is yttrium oxide (Y2O3). Yttrium oxide is used to make phosphors for color television sets and in crystals used in microwave detection instruments. [Pg.671]

The microwave detected MODR scheme closely resembles pulsed nuclear magnetic resonance (Hahn, 1950), optical coherent transients by Stark switching (Brewer and Shoemaker, 1971) and laser frequency switching (Brewer and Genack, 1976). The on-resonance microwave radiation field, ojq = ( 2 — Ei)/H, creates an oscillating bulk electric dipole polarization (off-diagonal element of the density matrix, pi2(t)). The oscillation is at u>o u>r, where ojr is the (Mj-dependent) Rabi frequency,... [Pg.435]

CO = 27t -35 Ghz. (a) The intensities /+, Iq and / of the three individual Zeeman components of the 0,0 transition of the 7 So phosphorescence at 20 192 cm were measured as functions of the applied magnetic field Bq for constant microwave power, (b) The ESR spectrum measured with the usual microwave detection. After [20]. [Pg.204]

Microwave detection can be performed from the penetrating side (pulse-echo mode) or from the opposite side (through-transmission mode). The through-transmission technique can determine the slate of resin cure in boron fiber laminates. However, it is not suitable for laminates with 0 /60 filament orientation [87]. The propagation of micro-waves (wavelength 10 10 m) is governed by Maxwell s equations of the magnetic field [88]. Maxwell s equations are... [Pg.800]

Ganchev, S. 1.. Carriveau. G.. and Qaddoumi, N. (1994), Microwave detection of defects in glass reinforced polymer composites. Proc. of the SPIE, Advanced Microwave and Millimeter-wave Detectors Conf.. Vol. 2275, pp. 11-20. [Pg.836]

There have been only a few coherence experiments on triplet states in the presence of an external magnetic field. Brown and Kreilick (1975) have described the development of (microwave-detected) FT echo modulation... [Pg.226]

The experimental development of infrared-microwave double resonance was paralleled by the elaboration of the theoretical framework. For example, Shimizu published a theory of two-photon Lamb dips, and Takami theoretically described the optical-microwave double resonance with emphasis to fundamental aspects and the double resonance with microwave detection, and with optical detection. Detailed information on the theory of infrared-microwave double resonance can also be found in Refs. 216, 225-227. [Pg.53]

The most widely used and in many cases most sensitive way of recording EPR spectra is continuous-wave (CW) EPR. In this experiment, microwave with constant frequency is irradiated with relatively weak power (typically between 1 jlW to 200 mW) and the magnetic field is swept to Irring the transitions into resonance. As broadband microwave detection by diodes is used, the detection bandwidth has to be limited by other means to avoid accumulation of excessive noise over a wide frequency range. This is achieved by low-frequency (typically 100 kHz) modulation of the magnetic field with an amplitude of 0.01-1 mT and phase-sensitive detection of the signal component modulated with this frequency. As a result, the derivative of an absorption lineshape is measured, which is better resolved than the absorption lineshape itself The technique is disadvantageous if all features of the absorption lineshape are much broader than the maximum modulation amplitude that can be technically achieved. [Pg.227]

Henck SA, Mason MA, Yan W-B, Lehmann KK, Coy SL (1995) Microwave detected, microwave-optical double resonance of NH3, NH2D, HND2, and ND3. I. Structure and force field of the A state. J Chem Phys 102 4772... [Pg.75]

U. Kretzer, 2001, GaAs wafer mapping by microwave-detected photoconductivity , Mater. Sci. Eng. B 80, 206-209 (see also R. Kremer, St. Teichert, 2003, "GaAs-based devices how to choose a suitable substrate . Comp. Semicond., 9, No. 4, 35-36). [Pg.99]


See other pages where Microwave detection is mentioned: [Pg.345]    [Pg.134]    [Pg.32]    [Pg.218]    [Pg.220]    [Pg.621]    [Pg.418]    [Pg.435]    [Pg.115]    [Pg.146]    [Pg.166]    [Pg.197]    [Pg.220]    [Pg.224]    [Pg.186]    [Pg.218]    [Pg.220]    [Pg.188]   
See also in sourсe #XX -- [ Pg.544 ]




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