W-band spectrum

The single line spectrum at X-band of the anion radical was attributed to unresolved hfc due to hydrogen and nitrogen. The g-anisotropy is small and is smeared out. In addition to the partly resolved g-anisotropy, features attributed to hfc due to nitrogen were observed on the high-field wing of the W-band spectrum. At 360 GHz the principal g-values were resolved to such extent that they could be directly read from the spectrum, see Fig. 4.3. 

Fig. 13.1 Multibubble sonoluminescence spectrum obtained from argon-saturated water sonicated at a frequency of 108 kHz with an ultrasonic power of 7.9 W. The spectrum consists of a broad continuum and OH radical bands...

Jevons, W. Spectroscopic investigations in connection with the active modification of nitrogen IV - a band spectrum of boron nitride. Proc. Roy. Soc. Lond 91A, 120-134 (1915). 

Alteration of the silver plasmon band spectrum upon electron and hole injection has been rationalized in terms of changes in the density, Ne, and conductivity, o, of the electron gas in the metal particles as described by Eqs. (16)—(18) [506]. Thus, a decrease in Ne by electron extraction from the metallic silver particles increases Xc (Eq. 16) and thereby shifting the absorption maximum (Eq. 15) of the plasmon band to a longer wavelength (Fig. 83). A decrease in Ne also decreases a (Eq. 18), which leads, in turn, to an increase of w (Eq. 17) that is, to an increase in the bandwidth of the plasmon band absorption (Fig. 83). Similarly, the increase in Ne by electron transfer to the silver colloids is paralleled by a decrease in Xc (Eq. 16) and, hence, by a decrease in Xm (Eq. 15), as seen by the shift of the plasmon absorption band to a shorter wavelength (Fig. 83). Electron donation to the silver particles also causes an increase in cr (Eq. 18)... 

The angle dependence of the spin soliton in randomly oriented ladder poly-diactylene has also been investigated79 by pulsed HFEPR at 94 GHz. The shape of the 0-anisotropy-resolved nutation spectrum was discussed on the basis of the EPR transition moments and the differences between spin relaxation times. Reliable assignments of hyperfine couplings to the p-protons (P-H) of the alkyl side chains were achieved with the support of W-band ENDOR measurements. No significant orientational dependence of the 7i and Ti processes was found in terms of the isotropy of the p-H-hyperfine interaction. 

W. Steubing found that the intensity of the fluorescence of iodine vapour is weakened between the poles of a powerful electromagnet. The result has nothing to do with the Zeeman effect, and has no connection with effects produced by admixture with gases, solvents, etc. It is produced by a direct action of the magnetic field on the electrons causing the band spectrum weakening the individual vibrations. 

J. Pllicker and J. W. Hittorf also showed that with a condensed discharge, the vacuum tube glows with a white light. This gives a line spectrum which is identical with that of the spark discharge, but has no relation with the band spectrum just indicated. These observations were confirmed by A. Wiillner,... 

Elsasser, W., Mean absorption and equivalent absorption coefficient of a band spectrum, Phys. Rev., 34 1938. 

FIGURE 3.8 W-band EPR spectra of aligned single crystals of [Fe4(OCH3)6(dpm)6] at 5 K (only the S = 5 ground state is populated). Inset coupling scheme of the four Fe(III) (s = 5/2) centers. Additional smaller effects and structural isomers cause the spectrum to be more complex than anticipated.17... 

At pressures less than 1 Pa, hydrogen atoms are formed by heated wires of W, Pd, or Pt. Under such conditions, concentration hydrogen atoms up to 95% may be obtained using a discharge tube. The half-life of the H atom is about 1.0 s at 30 Pa, which allows it to be transported out of the discharge and its reactions examined. The presence of hydrogen atoms in such experiments is established by observation of the Balmer series of the H atom spectrum and the diminution in intensity of the H2 molecules band spectrum. The very long half-life shows that only about 1 in 10 collisions between atoms leads to recombination. 

Fig. 27. (7) Excitation spectrum of the u.v. emission of YTaO4 at 300 K. (2) Reflection spectrum of YTaO4. W Emission spectrum of YTaO4 at 300 K under optical band gap excitation. (4) Emission spectrum of YTaO4 at 77 K under excitation below the optical band gap, viz. 254 nm. After Ref. 42...

An important feature of ultraviolet absorption spectra is that chromophores that are not conjugated give, not ir ir bands, but a summation of n w bands. A -CH2- group is sufficient to isolate two chromophores, but -0-, -S-, or -NH- is not. An example of this effect is seen for hexacene, a green compound, and 6,15-dihydrohexacene, a colorless compound whose absorption spectrum is essentially the sum of the spectra of anthracene and naphthalene ... 

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