Peak Separation double

Mass spectra of pyrrolidine derivatives of methyl or ethyl esters The molecular ions are intense with characteristic fragment ions at m/zs 70, 98, and 113. The position of the double bond can be determined by locating two peaks that differ by 12 mass units. A relatively intense peak should be observed 26 m/z units higher than the lower mass peak. The double bond lies between the two peaks that are separated by 26 Daltons. 

Sodium has 1 valence electron, and 10 bound electrons. The first two excited states are the 3 Pi/2 and the 3 P3/2 states. Transitions to these levels give rise to the Di and D2 transitions respectively. There are two h)q)erfine levels in the 3 ground state, and four h)q)erfine levels in the 3 Pa/2 excited state (Fig. 3). There is no significant energy difference between the h)q)erfine levels in the 3 Pa/2 state. Thus, the six permitted fines appear in two groups, producing a double peaked spectral distribution, with the peaks separated by 1.772 GHz. 

M l s-1), and then decrease. The decrease is caused by separation of the single peak into two individual peaks. The double peak phenomenon, which has been previously ascribed to the depletion of the reactant at low concentrations of M, has also been found to occur experimentally (5b). This phenomenon can be visualized by considering the effect of k in two ways. The first and most... 

Typical examples for strong coupling are the dimeric aggregates which exist in more concentrated aqueous solutions of many dyes such as thionine or the rhodamines " . Their absorption spectra are much broader than those of the monomers and, in several cases, consist of two distinct components with peak-to-peak separations of 1000 cm" or more, and comparable to the monomer band width. Similar but somewhat smaller splittings occur in the spectra of some double molecules, such as the p-cyclophanes and hydrogen-bonded dimers . 

The goal of most NMR spectroscopy is a chemical-shift spectrum, because this interaction is the source of NMR s remarkable utility as a molecular characterization tool. While a given nuclide is said to precess at the Larmor frequency, the exact precession frequency for a particular nucleus depends on its chemical environment. Chemical-shift frequencies scale with Bq, so field-independent ppm units are generally preferred in order to facilitate comparison among spectra recorded at different fields. Because chemical shifts (commonly designated by 8) are usually of only a few hertz, relative to the megahertz-scale Larmor frequency, they are usually expressed as parts per million, or ppm. In a 4.7-T magnet, will resonate at 50 MHz. A peak separation of 50 Hz corresponds to a chemical shift of 1 ppm (50 Hz/50 MHz). In a 9.4-T field ( C 100 MHz), these same peaks will be 100 Hz apart. While the difference, in frequency units, has doubled, the chemical shift is still 1 ppm (100 Hz/lOO MHz). The chemical-shift 5 scale is referenced relative to the frequency of a standard material. For example, in H, and Si NMR, the reference is tetramethylsilane (TMS), whose reso-... 

The band system Is now assigned to the 3p F2 3s electronic transition of the ammonium radical. The band system of ND4 (540 to 790 nm) shows a sharp principal band that is located at 674.8 nm. The principal band of NH4 Is diffuse and located at 663.6 nm. The principal bands of NH4 and ND4, assigned to the 0-0 transition, show characteristic prominent double peaks, separated by 6.92 (NH4) and by 6.24 cm" (ND4) [15], that probably result from the spin splitting of the upper state. Above and below the principal band are other bands that show double or multiple peaks see, for example [13]. In the case of ND4, two of these bands, situated 1100 cm below the principal band, were assigned to the 0-1 bands in the bending vibrational modes V2(E) and V4(F2). The assignment of the band system is complicated by the Jahn-Teller distortion of the upper state [6]. 

There are eases where the aetivated eomplex exists as an unstable intermediate. This is observed in reaetion profile as a trough in the aetivated peak of the eurve. This produees a double hump and as the minimum in the trough is more marked, that is, as the intermediate beeomes more stable, it beeomes more diffieult to separate the intermediate from the reaetion mixture during the eourse of the reaetion. Figure 1-3 shows the eurve of an unstable intermediate. 

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