X band, electron spin resonance

C16. Collier, R. J., Comment on X-band electron-spin-resonance (ESR) spectrometer with a ruby maser pre-amplifier. J. Sci. Instrum. 2, 912 (1969). 

Figure 20. Structural and spectroscopic properties of the spin-crossover complex [Ee(14)(OOr-Bu)(X)] (X = solvent or no ligand), (a) The DFT- optimized structure, (b) electronic spectra (233 K), (c) resonance Raman spectra (77 K), (d) X-band electron paramagnetic resonance (EPR)...

Fig. 12. Electron spin resonance spectra recorded at X-band for powdered clay samples at ambient laboratory temperature (a) montmorillonite, (b) kaolin, (c) Bentonite (Aldrich Chemical), (d) Bentonite (SSP/NF), (e) Magnabrite, (f) Polargel, (g) Volclay, and (h) Fuller s Earth (68).

Electron Spin Resonance. The ESR spectra of reduced and unreduced catalysts were recorded on a Bruker ER 200D-SRC X-band spectrometer with 100 kHz modulation at ambient temperature. Reduced catalysts for ESR study were prepared according to the procedure described elsewhere ( ). After hydrogen reduction at 300°C for h the sample was evacuated at the same temperature for 2 h and sealed off under vacuum. 

The electronic structure of tetrahedral oxyanions and their derivatives has been extensively studied by many authors during the past decades. The earlier attempts were summarized by Prins [1]. Since the work of Walsh [2] and that of Wolfsberg and Helmholz [3] several semi-empirical theoretical studies have been published [4-7]. Later ab initio [8-10] and scattered wave calculations [11] have been also reported. Among the experimental investigations, Prins mentioned the electron spin resonance measurements of radicals formed by ejection or addition of an electron from or to certain oxyanions, obtaining information on just those molecular orbitals which contained unpaired electrons. [12] X-ray absorption and emission studies provided usefial information on a limited number of molecular orbitals in the valence band [13-19]... 

Electron spin resonance (ESR) spectra were recorded at room temerature on powdered samples packed in columns in ESR tubes using an X-band spectrometer Varian Associates model E-109, operating at a 100 KHz modulation and a... 

ESR measurements were made at x-band frequency with a Varian E-3 electron spin resonance (ESR) spectrometer using 4mm quartz tubes. The magnetic field was varied from 0 to 5,000 G. The spectra were taken at room temperature and stored in a Nicolet LAS 12/70 Signal Averager. 

Electron Spin Resonance (ESR) Studies ESR spectra were measured with an X-band ESR spectrometer (Varian E-12, 100 KHz field modulation). To avoid distortion of the spectra by a power saturation, the ESR measurements were carried out at a microwave of 3mW. The g-value was measured by comparison with the strong pitch provided by Varian Associates. In all cases, ESR spectra were recorded at 77 K. 

The measurements of ESR spectra were made by use of Electron Spin Resonance Spectrometer Model JES-ME-3X made by Japan Electron Optics Laboratory Co. Ltd. with X band and magnetic field... 

Electron spin resonance (ESR) measurements were made with a Varian E-3 spectrometer operating at an X-band frequency. Samples were prepared by compression molding as previously described. A quartz solution cell made by Wilmad Glass Co. was used for measurements on solutions. 

Detection of hydroxyl radical. For detection of hydroxyl radicals, a spin trapping agent, DMPO was obtained from Sigma-Aldrich.4 The water containing 500 pM DMPO was circulated for 30 min in exPCAW-l,and the water was sampled at 0, 1, 5, 10, 15, 20, 30 min of circulation and exposure to UV, USW and elevated 02. The samples in a flat-shaped quartz ESR cell were analyzed with an electron spin resonance spectrometer (JEOL-TE200, X-band). DMPO-OH signal were collected with a sweep width of 5 mM, a 100 kHz modulation frequency, 60 s sweep time, a time constant of 0.1 s and microwave power of 10 mW, at room temperature of 20-25°C. 

Electron spin resonance spectrometers are available commercially, and typical operating conditions are a frequency/of 10 ° cps (x band), and a magnetic field H of 3600 gauss. Sometimes the measurements are made at other frequencies such as 2.4 X 10 cps (k band). The samples may be examined as a function of the microwave power, the microwave frequency, the modulation conditions, and the temperature. 

Electron spin resonance (ESR) spectroscopy is a very powerful and sensitive method for the characterization of the electronic structures of materials with unpaired electrons. There is a variety of ESR techniques, each with its own advantages. In continuous wave ESR (CW-ESR), the sample is subjected to a continuous beam of microwave irradiation of fixed frequency and the magnetic field is swept. Different microwave frequencies may be used and they are denoted as S-band (3.5 GHz),X-band (9.25 GHz), K-band (20 GHz), Q-band (35 GHz) and W-band (95 GHz). Other techniques, such as electron nuclear double resonance (ENDOR) and electron spin echo envelope modulation (ESEEM) spectroscopies, record in essence the NMR spectra of paramagnetic species. 

Electron spin resonance has been reported on Yb and Nd impurities in EusGasOn (Hodges, 1975). The particular interest in this host is that the Eu ion has a singlet ground state and the lines are not broadened by the host. Microwave losses of GdsGasOn have been measured at 30 GHz, X-band, and 2 GHz by Adam et al. (1975). These measurements in this host are important in technological applications, as it is used as a nonreciprocal thin film substrate. 

---