Spectrograph, mass

To calculate the chemical atomic weight of hydrogen from data obtained by the mass-spectrograph. 

TTie following values have been obtained by the most precise mensurements with the mass-spectrograph for atomic masses relative to = 16, i.e. on the physical scale (Aston, Mass spectra and isotopes , Arnold, 1942, p. 116) 

Several determinations have been made of the abundance ratio for hydrogen in certain natural waters and the values found for the ratio of to D vary between 5400 and 7020. (Tenth report of the Commission on Atomic Weights, J. Chem. Soc. 1940, 475). 

From the abimdance percentages for oxygen we calculate the ratio 0/ 0. This gives the conversion factor from the chemical scale 0 == 16 to the physical scale 0 = 16. 

We calculate the atomic mass of H on the physical scale, assuming the alternative extreme values for the abundance ratios, and we convert to the chemical scale. 

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It is widely used as filaments for mass spectrographs and ion gauges. Rhenium-molybdenum alloys are superconductive at 10 K. 

Mass spectrograph. An instrument in which beams of ions are separated according to their mass-to-charge ratio (m/z) and in which the deflection and intensity of the beams are recorded directly on a photographic plate or film. 

F. W. Aston (Cambridge) discovery, by means of the mass spectrograph, of isotopes in a large number of non-radioactive elements and for enunciation of the whole-number rule. 

When chlorine, CU, is examined in a mass spectrograph, Cl/, Cl+, and Cl+I ions are formed. Remembering that there are two isotopes in chlorine, 35 (75%) and 37 (25%), describe qualitatively the appearance of the mass spectrum. Which ion will produce lines at the largest radius Which at the smallest radius How many lines will each ion produce ... 

In a mass spectrograph, the factors that determine the trajectory of the ions are the same as those we discussed when we considered the measurement of (e/m) for the electron. In that discussion we derived equation 19) ... 

Describe the spectrum produced on a photographic plate in a mass spectrograph if a mixture of the isotopes of oxygen ( O, nO, and lcO) is analyzed. Consider only the record for +1 and +2 ions. 

Hydroxylamine, NHjOH, is subjected to electron bombardment The products are passed through a mass spectrograph. The two pairs of lines formed indicate charge/mass ratios of 0.0625,0.0588 and 0.1250,0.1176. How can this be interpreted ... 

Mass-energy relationship, 121 Mass number, 90, 120 Mass spectrograph, 242, 443 Mass spectrum of neon, 242 Matter... 

The isotope dilution principle, first employed by Hevesy and Hobbie (133) in 1932 for the determination of lead in ores, was applied by Schoenheimer et al. (241) to the determination of amino acids. [Shemin and Foster (248) have reviewed this topic.] An N15-amino acid derivative was added to a protein hydrolyzate, a sample of the amino acid to be determined was isolated and purified, the excess N15 in this product was estimated with the mass spectrograph, and the grams of amino acid originally present were calculated from Equation 2. 

Reynolds, F. L., E. K. Hulet and K. Street Mass Spectrographic Identifi-... 

Table VIII shows the results of a CH3—CH=CD2 isomerization run. Product analysis was carried out by IR and mass spectrographic analysis.

The earlier stable isotope dilution mass spectrographic work was accomplished with a thermal ion mass spectrometer which had been specifically designed for isotope abundance measurements. However, Leipziger [829] demonstrated that the spark source mass spectrometer could also be used satisfactorily for this purpose. Although it did not possess the excellent precision of the thermal unit, Paulsen and coworkers [830] pointed out that it did have a number of important advantages. 

When a beam of alkyl radicals and hydrocarbons from a furnace in which a lead tetraalkyl is decomposing is crossed with a beam of electrons, the resulting ions can be identified by the mass spectrograph... 

Recently, a quantitative electrospray ionization/mass spectrometry method (ESI/MS) has been developed to analyze the molecular profile, or hpidome of different lipid classes in very small samples. In this method, total lipid extracts from tissues or cultured cells can be directly analyzed. By manipulating the ionization method, the mass spectrographs of polar or even non-polar lipids can be obtained [8]. This method and the use of lipid arrays allow precise and quantitative identification of the lipid profile of a given tissue, and map functional changes that occur. 

N. B. Hannay. Mass Spectrographic Analysis of Solids High Sensitivity for Bulk and Surface Impurities is Provided by a New Analytical Method. Science, 134(1961) 1220-1225. 

D. T. Young, J. A. Marshall, J. L. Burch, T. L. Booker, A. G. Ghielmetti, and E. G. Shelley. A Double-Focusing Toroidal Mass Spectrograph for Energetic Plasmas. II Experimental Results, Nucl. Instr. and Meth., A258(1987) 304. 

The stability of complex fluorides in molten salt solutions has also been widely investigated. The studies of cryolite and chiolite in NaF/AlF3 melts by cell methods (67) or by mass-spectrographic examination of vapor species (150) are typical. 

Most practitioners of the precise art and subtle science of mass spectrometry acknowledge the field to have originated with the work of J.J. Thomson (Fig. 19.1) and associates, [6] published in 1910-1912, using the parabola mass spectrograph. Seminal discoveries that he and his coworkers made include the fact that the elements could be polyisotopic, by discovering the isotopes of neon. Thomson was awarded the Nobel Prize in physics of 19062 for his work on investigations on the conduction of electricity by gases. ... 

Abstract A brief introduction deals with the time period from Dalton to the discovery of isotopes by Soddy and Fajans in the early twentieth century which was soon followed by the invention of the mass spectrograph (1922). The next section covers the period from 1922 to the discovery of deuterium by Urey and his colleagues. It includes a discussion of isotope effects in spectroscopy, particularly band spectra of diatomic molecules, and also discusses the discovery of the important stable isotopes in the second row of the periodic table. It ends with the discovery of deuterium, probably the most popular isotope for isotope effect studies. The chapter ends with a short description of the apparatus of theory and experimentation available for isotope effect work at the time of the discovery of deuterium. 

From the Discovery of Isotopes through the Invention of the Mass Spectrograph by Aston... 

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