Micro wave spectra

The molecular data obtained from the infra-red spectra (see Table 1) are in good agreement with the results from micro-wave spectra >29). 

R. L. Brown, L. Burnelle, M. A. A. Clyne, F. Kaufman and J. C. Polanyi have provided us with the results of their researches prior to publication. F. Kaufman and H. I. Schiff have aided with comments on parts of this paper. F. R. Gilmore, M. A. A. Clyne, E. A. Ogryzlo and B. A. Thrush have kindly provided figures. Professor Polanyi, the Chemical Kinetics Information Center (NBS), the Micro-wave Spectra Data Center (NBS) and the Diatomic Molecule Spectra and Energy Level Center (NBS) have supplied us with an abundance of reference material. The organization of the bibliography, tabular material and the typescript has been done by Mrs. M. C. Peter. To all of these we express our appreciation. 

Structural data so far obtained from X-ray analyses, electron diffractions, micro-wave spectra, NMR-coupling constants etc. are also mentioned. 

The structures of cis and trans-1,2-difluorocyclopropane obtained from their micro-wave spectra are in general agreement with theoretical studies ... 

The pyrazole molecule is planar. Bond lengths and bond angles have been calculated from micro-wave spectra (see Fig. 5.16). Consistent with the structural formula, the bond between atoms 3 and 4 is the longest. 

The micro-wave spectrum of OCS contains the following observed lines due to ( Molecular micro-wave spectra tables , Kisluik... 

The aromatic character of 1,3,4-thiadiazole can be demonstrated with the aid of micro-wave spectroscopy. Using the differences between the measured bond lengths and covalent radii, aromaticity, as shown by 7r-electron delocalization, diminishes in the order 1,2,5-thiadiazoles > thiophene > 1,3,4-thiadiazole > 1,2,5-oxadiazole (66JSP(19)283). The micro-wave spectrum was further refined by later workers (7lJST(9)l63). 

If a molecule contains an atom with a nucleus having nuclear spin I > 1/2 (e.g., N or Cl), the observed micro-wave spectrum will be more complex due to the electron-nuclear hyperfine interaction as well as nuclear qua-drupole interactions (23,24). For each of the three electron-spin directions, there are a number of different nuclear spin quantization directions. For nitrogen,... 

To determine the moment of inertia and rotational characteristic temperature of OCS from its micro-wave spectrum. 

The micro-wave spectrum of NHj shows strong absorption over a region around 23 x 10 c/s. A detailed interpretation of this spectrum shows that the "zero line due to a transition between the two vibrational levels each in the ground rotational state occurs at 23 785.8 Mc/s (Strandberg, Kyhl, Hillger, and Wentink, Phys. Rev. 1947, 71, 326). 

The micro-wave spectrum is the pure inversion spectrum between the two ground states. 

From the micro-wave spectrum we conclude that the separation in the ground state is... 

When the (effective or real) g-values can be read from the spectrum (with Equation 2.6) then the factor I is known, and the EPR equivalent of Beer s law at fixed micro-wave frequency, v, has no unknowns except for the concentration c... 

Suppose we want to compare two spectra—let s call them spectrum-a and spectrum-P—taken over field sweeps that may be identical but with a slight difference in their micro-wave frequency. The spectra are digital arrays corresponding to amplitudes at equidistant field values. The procedure to convert spectrum P taken at frequency vp to frequency va of reference spectrum a is as follows For each field value B of spectrum-a we calculate the corresponding field for vp /ip = (vp/va)5a, and then we search in spectrum-p to the two digital field values that nearly match (that embrace ) the value /ip in order to interpolate the two corresponding amplitudes to an intermediate amplitude value for flp to be stored in a new array of P-amplitudes onto a B(J grid. In pseudo-code... 

From 1972 to the present, samples of TTBP and related derivatives have been sent by Schmutzler and ourselves to many experts in electron diffraction or micro-wave spectroscopy but, despite this, the molecular geometry of TTBP still remains unknown. From the long discussions we had with these experts, it appears that the main reasons for this failure are as follows the TTBP molecule contains 27 hydrogen atoms and it would have been tedious to prepare the complete set of deuterated species and analyse them by means of microwave spectroscopy, which would have been essential to obtain an unambiguous geometry. As for electron diffraction, the main difficulty arose from the fact that no simple intuitive model could be built to fit the experimental spectrum. We shall see why later. 

The structure of 1,1-difluorobenzocyclopropene (21), as determined by micro-wave spectroscopy, exhibits some deviations from that determined by X-ray methods. The discrepancies may be due to the fact that the microwave spectrum was only measured from a single isotopomer, since at the time, no isotopically... 

A six- or four-line ESR spectrum that can be fitted to a triplet spin Hamiltonian is strong evidence that the species in the sample embodies two unpaired electron spins. Support for the presence of a triplet spin system often can be found in the weak Ams = 2 line, which appears at one-half the field strength of the center of gravity of the Ams = 1 six-line pattern. This nominally forbidden Amj = 2 resonance results when the ESR spectrometer field and frequency produce a micro-wave quantum of energy just sufficient to jump the gap between the uppermost and lowermost triplet substates, that is, a transition over two quantum levels. 

The setup for ESR spectroscopy is a cross between NMR and micro-wave techniques (Section 5.8). The source is a frequency-stabilized klystron, whose frequency is measured as in microwave spectroscopy. The microwave radiation is transmitted down a waveguide to a resonant cavity (a hollow metal enclosure), which contains the sample. The cavity is between the poles of an electromagnet, whose field is varied until resonance is achieved. Absorption of microwave power at resonance is observed using the same kind of crystal detector as in microwave spectroscopy. Sensitivity is enhanced, as in microwave spectroscopy, by the use of modulation The magnetic field applied to the sample is modulated at, say, 100 kHz, thus producing a 100-kHz signal at the crystal when an absorption is reached. The spectrum is recorded on chart paper. 

The method of phosphorescence microwave double resonance (PMDR) spectroscopy is based, like the two other methods discussed above, on c.w. excitation of the Pd(2-thpy)2 compound at low temperature. Additionally, micro-wave irradiation is applied, whereby the frequency is chosen to be in resonance with the energy separation between the two substates I and III of 2886 MHz. With this set-up, one monitors the phosphorescence intensity changes in the course of scanning the emission spectrum. Technically, the phosphorescence spectrum is recorded by keeping the amplitude-modulated microwave frequency at the constant value of 2886 MHz and by detecting the emission spectrum by use of a phase-sensitive lock-in and signal averaging procedure (e.g. see [61, 75,90]). 

Electromagnetic radiation in the microwave frequency spectrum is absorbed most strongly by molecules with permanent dipole moments (4). The relaxation phenomenon of this absorbed power manifests itself in a heatlike reaction. The University of Colorado Oil Shale Project has studied the degradation of the liquid-fuel precursor (kerogen) by micro-wave interaction. Kerogen is a moderately strong absorber of this radia-... 

It was then demonstrated that the infrared domain was part of the electromagnetic spectrum which extends from gamma rays to radio waves. The infrared range is situated between visible radiation (400-800 nm) and micro-waves (approximately 10 nm). 

Goodwin, E.J. and Legon, A.C. (1984) The rotational spectrum of the weakly bound molecular complex OC-HCN investigated by pulsed-nozzle, Fourier transform micro-wave spectroscopy. Chem. Phys., 87, 81-92. 

Nonionizing radiation consists of parts of the electromagnetic spectrum that correspond to microwaves, also identified as RF waves and extremely low frequency (ELF) waves. RF waves range from 300 MHz to 30 GHz and correspond to AM radio, FM radio, TV, mobile telephone, and micro-wave oven transmissions. ELF waves are in the 50-60 Hz range and correspond to electrical transmission power line emissions. 

Because of the demonstrated success achieved with electrochromism in CPs, there is an ongoing search for a CP-based device capable of modulating the entire spectrum from the visible through the IR to the micro-wave region. 

Use the diagram of the electromagnetic spectrum below to list the following types of radiation in order of increasing wavelength micro-waves that cook food, ultraviolet radiation from the sim, X rays used by dentists and doctors, the red light... 

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