Spectrogram

In a mass spectrometer, the molecules, in the gaseous state, are ionized and fragmented. The fragments are detected as a function of their mass-to-charge ratio, m/e. The graphical representation of the ion intensity as a function of m/e makes up the mass spectrogram as illustrated In Figure 3.1. 

Hyperfine stmcture measurements of 75 strong lines at 4020—6200 mm were made by means of interferometer spectrograms. Doublet stmctures occurred in 30 lines with separations of 0.034—0.180 cm ( )- Nuclear spins for Pu and for Pu have been estabUshed to be / = 1/2 and 1 = 5/2, respectively. The spins were based on paramagnetic resonance measurements on a RbPu02(N02)3 crystal (77). 

The orientation of crystallites in PET fibers can also be assessed quantitatively by means of IR spectro-graphic examination. In this case, the basis for the assessment are the values of dichroic ratio (R) of the crystalline absorption bands in the fiber spectrogram. The determination of the values of fc is made using Fraser s dependence [24,25] modified by Chranowski [26] ... 

For quantitative analysis it is necessary to assess the densities of blackening of lines in a spectrogram due to the constituents being determined this may be done by comparing the spectra from samples of known and unknown composition. Comparisons may be made either visually (best with the aid of a spectrum projector see Fig. 20.6) when no great accuracy is desired, or by photoelectric... 

Photodiodes are the modem analogues to photocells. They increase their electrical resistance under light impact which, as part of an electric circuit, can be measured easily. Many current instruments display diode arrays instead of a single diode. Tens of photodiodes are arranged in a tight area. They are exposed to the sample bound spectrum where they respond to the color that corresponds to their positions in the diode array. A rapid, periodically performed electrical interrogation of all diodes (sequence periodicity in the order of milliseconds) reveals a quasi-stationary stable spectrogram. More sophisticated than photodiodes are phototransistors. They amplify internally the photoelectric effect, but the sensitivity of a photomultiplier cannot be achieved. 

Figure 7.15 Superposition of the ESI mass spectrograms of the [Ce2], [Er2] and [CeEr] complexes, emphasizing the absence of the characteristic peaks from any of the homometallic analogues on the graph from the heterometallic species.

Attention should be paid to the appearance of spurious peaks in the fragmentation patterns of amines determined by GC-MS, when the analytes came into contact with methanol or ethanol as solvents. Thus, for example, Schiff bases may be formed on condensation of a primary amine with traces of formaldehyde or acetaldehyde present in the solvent. Although the peaks of such product may be unresolved in the chromatogram, they may appear as ions with mass increments of +12 or +26 in the mass spectrogram, complicating the identification of the analyte, as was the case with some amphetamine drugs99. 

Ionization in a Detonation Wave. Hay et al (Ref 9) obtained high-speed framing camera pictures and time-resolved spectrograms of the... 

LL) F. Pristera et al, PATR 2254(1956) (Analysis of Explosives by Infrared Spectroscopy). A compilation of 68 infrared spectrograms covering all common HE s and many possible expl ingredients, additives and related compds. In the analysis of single or multi-component HE s, infrared specttoscopy is, in most cases, very useful either alone or in connection with other methods. Infrared spectroscopy has the advantages of speed, specificity and very often accuracy precision... 

Catalog of Infrared Spectrograms, Sadtler Research Laboratories, Philadelphia, PA, spectra indexed by name and by major bands. 

Figure 10.6 Two-dimensional REMPI spectrogram of the centrifuged Oj molecules. Ion signal is color coded as a function of the frequency of the ionizing laser field, which undergoes two-photon absorption on the C Yl v = 2) X L v" = 0) transition, and molecular angular momentum, which is defined by...

The standard against which all peak intensities in a given mass spectrogram are measured is the most intense peak, called the base peak, which is arbitrarily assigned the value 100. If few parent molecules fragment—not a typical situation—the parent cation will furnish the base peak. 

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