scholarly journals Role of Helium Droplets in Mass Spectra of Diatomics: Suppression of Dissociative Reactions

2015 ◽  
Vol 28 (4) ◽  
pp. 489-492 ◽  
Author(s):  
Andrew M. Ellis ◽  
Sheng-fu Yang
Keyword(s):  
Mass Spectra ◽  
Helium Droplets ◽  
Dissociative Reactions

CAPPED METAL CLUSTERS IN THE GAS PHASE

2005 ◽  
Vol 04 (05n06) ◽  
pp. 935-944 ◽  
Author(s):  
JOBIN CYRIAC ◽  
V. R. RAJEEV KUMAR ◽  
T. PRADEEP
Keyword(s):  
Gas Phase ◽  
Chain Length ◽  
Column Chromatography ◽  
Mass Spectra ◽  
Metal Clusters ◽  
Laser Desorption ◽  
Gold Clusters

Alkanethiol protected gold clusters of 29 kDa were prepared and separated by column chromatography. Laser desorption mass spectra of these clusters have been investigated. In the gas phase, monolayer–monolayer interaction leads to clustering of the protected clusters. Role of different matrices and effect of alkanethiol chain length on this process have been investigated.

Mass Spectrometry of N-Benzoyl-2-hydroxyalkylamines. Role of the Hydroxylic Hydrogen in the Fragmentation Pattern

1975 ◽  
Vol 53 (21) ◽  
pp. 3175-3187 ◽  
Author(s):  
Don C. DeJongh ◽  
Denis C. K. Lin ◽  
Pierre LeClair-Lanteigne ◽  
Denis Gravel
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Hydroxyl Group ◽  
Fragmentation Pattern ◽  
Relative Importance ◽  
Hydrogen Atoms ◽  
Related Compounds ◽  
Double Hydrogen ◽  
Hydrogen Rearrangement

An interesting rearrangement has been observed in the mass spectra of a series of N-benzoyl-2-hydroxyalkylamines. The hydrogen atom of the hydroxyl group is transferred to the N-benzoyl portion of the molecular ion and the bond between positions 1 and 2 in the N-alkyl group is cleaved. A rearrangement ion, observed at m/e 135, is formed along with a neutral aldehyde or ketone. When the hydroxylic hydrogen is replaced by a trimethylsilyl substituent, the latter group is transferred with comparable efficiency. Differences in the relative importance of this rearrangement in the mass spectra of a series of related compounds with decreasing substitution at position 2, have been explained by differences in the stabilities of the neutral molecules formed along with m/e 135 and by the occurrence of a double hydrogen rearrangement which competes if hydrogen atoms are present in a relationship gamma and delta to the carbonyl group.

Derivatization in Mass Spectrometry—1. Silylation

2003 ◽  
Vol 9 (1) ◽  
pp. 1-21 ◽  
Author(s):  
John M. Halket ◽  
Vladimir G. Zaikin
Keyword(s):  
Mass Spectrometry ◽  
Structure Determination ◽  
Spectral Properties ◽  
Mass Spectra ◽  
Biologically Active ◽  
Chromatographic Mobility ◽  
Mass Spectral ◽  
Silyl Derivatives ◽  
Catalytic Stability

This is the first of a series of reviews on the application of derivatization in mass spectrometry. A description is given of advances in silylation as a powerful tool used for increasing the volatility, thermal and thermo-catalytic stability, and chromatographic mobility of polar and unstable organic compounds. In addition to chemical aspects of silylation, mass spectral properties of silyl derivatives useful for structure determination and quantitation of various organic and biologically-active compounds, mainly by GC/MS, are described. Practically all tested and widely used silylating agents are described. The role of comprehensive libraries containing reference mass spectra for various silyl derivatives and search systems in structure determination is emphasized. Applications of silylation for particular analyses are summarised.

Role of the support material on laser desorption/ionization mass spectra

2008 ◽  
Vol 22 (7) ◽  
pp. 925-929 ◽  
Author(s):  
A. Gruszecka ◽  
M. Szymanska-Chargot ◽  
A. Smolira ◽  
J. Cytawa ◽  
L. Michalak
Keyword(s):  
Mass Spectra ◽  
Laser Desorption ◽  
Ionization Mass ◽  
Support Material ◽  
Laser Desorption Ionization ◽  
Desorption Ionization

Lipophilic Compounds from the Femoral Gland Secretions of Male Hungarian Green Lizards, Lacerta viridis

2009 ◽  
Vol 64 (5-6) ◽  
pp. 434-440 ◽  
Author(s):  
Renata Kopena ◽  
Pilar López ◽  
José Martín
Keyword(s):  
Mass Spectra ◽  
Chemical Compounds ◽  
Reproductive Behaviour ◽  
Sexual Signals ◽  
Lizard Species ◽  
Specific Chemical ◽  
Lipophilic Compounds ◽  
Lacerta Viridis ◽  
Femoral Gland Secretions

In spite of the importance of chemical signals (pheromones) in the reproductive behaviour of lizards, only a few studies have examined the role of specific chemical compounds as sexual signals. The secreted chemicals vary widely between species but whether this variation reflects phylogenetic or environmental differences remains unclear. Based on mass spectra, obtained by GC-MS, we found 40 lipophilic compounds in femoral gland secretions of male green lizards (Lacerta viridis), including several steroids, α-tocopherol, and esters of n-C16 to n-C20 carboxylic acids, and minor components such as alcohols between C12 and C20, squalene, three lactones and one ketone. We compared these chemicals with those previously found in other closely related green lizard species, and discussed how phylogenetical differences and/or environmental conditions could be responsible for the differential presence of chemicals in different lizard species.

The role of pattern recognition in the computer-aided classification of mass spectra

1979 ◽  
Vol 112 (4) ◽  
pp. 407-416 ◽  
Author(s):  
William S. Meisel ◽  
Matt Jolley ◽  
Stephen R. Heller ◽  
George W.A. Milne
Keyword(s):  
Pattern Recognition ◽  
Mass Spectra ◽  
Computer Aided

scholarly journals EXTENDED PLANCK SCALE

2003 ◽  
Vol 18 (15) ◽  
pp. 1037-1042 ◽  
Author(s):  
F. I. COOPERSTOCK ◽  
V. FARAONI
Keyword(s):  
Z Boson ◽  
Mass Spectra ◽  
Planck Scale ◽  
Structure Constant ◽  
High Energy ◽  
Fine Structure Constant ◽  
High Energy Radiation ◽  
Planck Mass ◽  
Null Surface

Traditional derivations of the Planck mass ignore the role of charge and spin in general relativity. From the Kerr–Newman null surface and horizon radii, quantized charge and spin dependence are introduced in an extended Planck scale of mass. Spectra emerge with selection rules dependent upon the choice of Kerr–Newman radius to link with the Compton wavelength. The appearance of the fine structure constant suggests the possibility of a variation in time of the extended Planck mass, which may be much larger than the variation in the traditional one. There is a suggestion of a connection with the α value governing high-energy radiation in Z-boson production and decay.

The role of conformational mobility in the stereospecific loss of water under electron impact

1979 ◽  
Vol 44 (12) ◽  
pp. 3595-3603 ◽  
Author(s):  
František Tureček ◽  
Vladimír Hanuš ◽  
Miloš Tichý
Keyword(s):  
Electron Impact ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Conformational Mobility ◽  
Water Elimination

Mass spectra of nine of the sixteen possible diastereoisomeric 7-hydroxytricyclo[7.3.0.02,6]dodecanes are reported. The spectra differ considerably in the extent of water elimination from molecular ions. The diastereoisomers which have conformationally flexible cis-anti-cis, cis-anti-trans and cis-syn-trans skeletons exhibit abundant (M-H2O)+. ions. Molecular ions of the rigid trans-anti-trans isomers lose water to a markedly smaller extent, the main fragmentation proceeding via a skeletal cleavage. Effects of conformational mobility are emphasized.

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