This spectrum is called a Raman spectrum and corresponds to the vibrational or rotational changes in the molecule. The selection rules for Raman activity are different from those for i.r. activity and the two types of spectroscopy are complementary in the study of molecular structure. Modern Raman spectrometers use lasers for excitation. In the resonance Raman effect excitation at a frequency corresponding to electronic absorption causes great enhancement of the Raman spectrum.  [c.340]

Tetracyclines are broad-spectrum antibiotics. effective against Gram-positive and Gram-negative bacteria, also against Rickettsiae (typhus fever) and certain other organisms.  [c.390]

X-ray Electromagnetic radiation of wave length c. 1 k. X-rays are generated in various ways, including the bombarding of solids with electrons, when they are emitted as a result of electron transitions in the inner orbits of the atoms bombarded. Each element has a characteristic X-ray spectrum.  [c.429]

The spectrum of the secondary emission, that is, the intensity of X-ray radiation as a function of wavelength is established using a crystal analyzer based on Bragg s law.  [c.33]

The plasma comprises free positive and negative ions generally in equilibrium at high temperature. It has a high electrical and thermal conductivity and emits photons whose frequency is characteristic of the atoms present. The polychromatic rays are analyzed by a monochromator that gives the plasma s spectrum. The elements are identified by their wavelengths and the signal intensity is proportional to the quantity of ions present in the arc. The response is linear for. 5 or 6 orders of magnitude, something which gives a large advantage to the plasma technique over atomic absorption. Furthermore, the method is multi-elemental it permits the analysis of about 70 trace elements without having to change the device.  [c.37]

Mass spectrum for n-nonane (MW = 128).  [c.46]

Knowing and 2 by studying reference components, it becomes possible to calculate from the measurements of ion intensities found on the mass spectrum.  [c.49]

Bafmer series Frequencies of certain lines in the spectrum of hydrogen are simply related to each other, and can be expressed by a general formula. One group of lines is termed the Balmer series. Other series were later discovered in the spectrum of hydrogen by Lyman, Paschen, Brackett and Pfund.  [c.50]

Information from an n.m.r. spectrum is classified into the chemical shift, <5 (the relative shift from a standard [Me Si for H, CC13F for which is rendered independent of the field), and the coupling constants, J, which are determined directly from the spectra.  [c.282]

See pages that mention the term Spectrin : [c.9]    [c.9]    [c.40]    [c.41]    [c.41]    [c.45]    [c.45]    [c.48]    [c.50]    [c.79]    [c.89]    [c.99]    [c.110]    [c.110]    [c.141]    [c.181]    [c.217]    [c.240]    [c.252]    [c.261]    [c.264]    [c.267]    [c.282]    [c.288]    [c.296]    [c.310]    [c.326]    [c.331]    [c.337]    [c.338]    [c.347]    [c.356]    [c.361]    [c.368]    [c.369]    [c.393]    [c.407]    [c.412]    [c.419]    [c.419]    [c.419]    [c.27]   
Introduction to protein structure (1999) -- [ c.36 ]