High-Resolution Studies

An alternative to observing sample and reference together at high resolution involves the use of a double-beam mass spectrometer such as the AEI MS-30. If closely spaced mass multiplets need not be resolved, one can determine the exact mass of each peak in the spectrum at resolutions of 1500, the computer acquiring data from the independent sample and reference beams simultaneously (226). Thus, source conditions can be optimized for compound and reference at the higher sensitivities available at lower resolutions, the mass measuring accuracy still being in the order of 10 ppm. This is possible, since if mass doublets are not involved, the centroid of a peak is as well defined at resolution 1500 as at 10,000. 

Haegele et al. (269) have used exact isotope masses and isotope abundances together in determining the detailed fragmentation patterns of square planar rhodium (I) -diketonate complexes. They found that some species postulated by other workers were in error. High resolution is needed to distinguish the 28 mass units for loss of CO (27.9949) from C2H4 (28.0313) (269) or the 69 mass units for PF2 (68.9906) from CFa (68.9952) (90). 

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Conventional spontaneous Raman scattering is the oldest and most widely used of the Raman based spectroscopic methods. It has served as a standard teclmique for the study of molecular vibrational and rotational levels in gases, and for both intra- and inter-molecular excitations in liquids and solids. (For example, a high resolution study of the vibrons and phonons at low temperatures in crystalline benzene has just appeared [38].)... 

Plenary 9. J W Nibler et al, e-mail address niblerj chem.orst.edu (CARS and SRS). High resolution studies of high lymg vibration-rotational transitions in molecules excited in electrical discharges and low density monomers and clusters in free jet expansions. Ionization detected (REMPI) SRS or IDSRS. Detect Raman... 

Table 1 lists our abundances of Fe, C, O and a-elements for the observed clusters. An overall excess of a-elements is shared by all the clusters up to solar metallicity, consistent with SNell being responsible for the gas enrichment. Our findings are also in good agreement both with all previous high resolution studies (see [2], [3], [6]) and with recent abundance determinations for field stars in the Galactic Bulge (see [10]). 

R.L. Airs and B.J. Keely, A high resolution study of the chlorophyll and bacteriochlorophyll pigment distributions in a calcite/gypsum microbial mat. Org. Geochem. 34 (2003) 539-551. 

Moldovan, Z. Palibroda, N. Mercea, V. Mihailescu, G. Chiriac, M. Vlasa, M. Mass Spectra of Some P-Keto Esters. A High Resolution Study. Org. Mass Spectrom. 1981,76, 195-198. 

Although no high resolution studies have been reported for ammonia interaction with iron surfaces, two main states of adsorption were recognized. At 80 K adsorption is entirely molecular with a characteristic N(ls) binding energy of 400 eV, but on warming the adlayer to 290 K the N(ls) intensity is mainly at 397 eV, typical of chemisorbed nitrogen adatoms with only a small contribution at 400 eV. 

Apart from a recent 400 MFlz high resolution study of mango juice during ripening there does not appear to have been any systematic low-resolution or relaxation time NMR study of mango maturity. Kim et recorded the... 

For normal high-resolution studies, the detector has a fairly large aperture, typically 5-25 mm. There are some applications for position-sensitive detectors for low resolution triple-axis diffractometry. These are in essence gas-filled... 

Evans, S.V. Brayer, G.D. High-resolution study of the three-dimensional structure of horse heart metmyoglobin./. Mol. Biol. 1990, 213, 885-897. 

The crystal structure of human HO-1 complexed with heme has been determined to 2.07 A (163). In order to obtain crystals for high-resolution studies 164), it was necessary to use an E. coli expressed version of HO-1 consisting of residues 1-233 (missing residues 234-288, which includes the C-terminal membrane anchor). This shorter version of HO-1 is soluble and retains about 50% wild-type activity (165). As shown in Fig. 16, HO-1 is formed exclusively by helices and connecting segments of random coil. Although the rich helical content is similar to that of... 

Isotope Abundances Negative Ions Synthetic Models V. High-Resolution Studies VI. Metastable-Ion Techniques VII. Coupled Gas Chromatography and Mass Spectrometry Inorganic and Organometallic Compounds VIII. Conclusion. ... 

H. J. Freund and H. Kuhlenbeck, in Applications of Synchrotron Radiation High resolution studies of molecules and molecular adsorbates, edited by W. Eberhardt (Springer-Verlag, Berlin-Heidelberg, 1995), Vol. 35. 

It is interesting to note that in high-resolution studies of the spectra of solid hydrogen transitions were seen with a change of the rotational quantum numbers A J of 6 and 8 [102]. The suggestion was made that these could be caused by H2 multipole moments of higher order than the hexadecapole (or 24) moment, e.g., by the H2 26 and 28 multipole moments. Such transitions are weak and have hitherto not been included in any treatments of collision-induced absorption in gases. 

FCO has only been observed47 in CO and Ar matrices at low temperature. NF2 can be produced by thermal dissociation from N2F4 at moderate temperatures. Its infrared and ultraviolet absorption spectra have been studied.53-55 The ultraviolet bands are rather indistinct, and no high resolution studies of the infrared bands have been carried out. The FNF angle is estimated to be 104.2°. 

Butler et al. (175) measured the LIF spectra of the ground state of the CS radical, and found that it was produced vibra-tionally excited. Their vibrational distribution curve peaks at v" = 3 and extends to v" = 6 (see Figure 10). Their high resolution studies indicated that the rotational population could be described with a "temperature" of about 700 K. Addison et al. (176) directly measured the S(4i) concentration change in time using resonance fluorescence detection. From the time dependence they extrapolated the concentration back to zero time and determined the nascent atom concentration for the 4). The yield of the S(3p)/S(4)) ratio was obtained by measuring the... 

Small molecules are already at the limit of detectability as far as proton NMR is concerned, whereas they are easily detected through 2H NMR. If other factors concur favorably (interactions between radicals at high concentration, tendency to aggregate, availability of low-lying excited states), the proton NMR signals can also be detected for radicals. Nevertheless, it is, in general, a hard task to perform high resolution studies on radicals. 

M. Domke, K. Schulz, G. Remmers, G. Kaindl, D. Wintgen, High-resolution study of 1P° double-excitation states in helium, Phys. Rev. A 53 (1996) 1424. 

The rest of the apparatus is the same as when operated at the Proton Synchrotron. First tested on cesium [ HUB 78 ], [ THI 81 ] the apparatus was used to uncover the resonance lines of francium for which no optical transition had ever been observed. The CERN on line mass separator, Isolde, makes available a source of more than 10 atoms/sec of chemically and isotopically pure 213 Fr isotope. Such an amount is more than needed for a laser atomic beam spectroscopy. The first step is obviously to locate the resonance line at low resolution, using a broad band laser excitation. In a second step, once the line is located, a high resolution study is undertaken, [ LIB 80] and [ BEN 84]. The observed signal is displayed (fig 3a) at low resolution and(3 b)at high resolution. 

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