Formation and Fragmentation Chemistry of Tripositive Ln(TMGA)3 3+ Complexes in the Gas Phase

2017 ◽  
Vol 28 (8) ◽  
pp. 1696-1701 ◽  
Author(s):  
Xiuting Chen ◽  
Qingnuan Li ◽  
Yu Gong
Keyword(s):  
Gas Phase ◽  
Fragmentation Chemistry

Deprotonated carbohydrate anion fragmentation chemistry: structural evidence from tandem mass spectrometry, infra-red spectroscopy, and theory

2018 ◽  
Vol 20 (44) ◽  
pp. 27897-27909 ◽  
Author(s):  
Jordan M. Rabus ◽  
Daniel R. Simmons ◽  
Philippe Maître ◽  
Benjamin J. Bythell
Keyword(s):  
Mass Spectrometry ◽  
Infrared Spectroscopy ◽  
Tandem Mass Spectrometry ◽  
Gas Phase ◽  
Tandem Mass ◽  
Phase Structures ◽  
Infra Red ◽  
Fragmentation Chemistry

We investigate the gas-phase structures and fragmentation chemistry of deprotonated carbohydrate anions using combined tandem mass spectrometry, infrared spectroscopy, regioselective labelling, and theory.

scholarly journals Chemical aging of <i>m</i>-xylene secondary organic aerosol: laboratory chamber study

2011 ◽  
Vol 11 (9) ◽  
pp. 24969-25010 ◽  
Author(s):  
C. L. Loza ◽  
P. S. Chhabra ◽  
L. D. Yee ◽  
J. S. Craven ◽  
R. C. Flagan ◽  
...  
Keyword(s):  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Chemical Mechanism ◽  
Ionization Mass ◽  
Phase Reaction ◽  
Particle Phase ◽  
Chemical Aging ◽  
Volatile Products ◽  
Fragmentation Chemistry

Abstract. Secondary organic aerosol (SOA) can reside in the atmosphere for a week or more. While its initial formation from the gas-phase oxidation of volatile organic compounds tends to take place in the first few hours after emission, SOA can continue to evolve chemically over its atmospheric lifetime. Simulating this chemical aging over an extended time in the laboratory has proven to be challenging. We present here a procedure for studying SOA aging in laboratory chambers that is applied to achieve 36 h of oxidation. The formation and evolution of SOA from the photooxidation of m-xylene under low-NOx conditions and in the presence of either neutral or acidic seed particles is studied. In SOA aging, increasing molecular functionalization leads to less volatile products and an increase in SOA mass, whereas gas-phase or particle-phase fragmentation chemistry results in more volatile products and a loss of SOA. The challenge is to discern from measured chamber variables the extent to which these processes are important for a given SOA system. In the experiments conducted, m-xylene SOA mass increased over the initial 12-h of photooxidation and decreased beyond that time. The oxidation of the SOA, as manifested in the O:C elemental ratio and fraction of organic ion detected at m/z 44 measured by the Aerodyne aerosol mass spectrometer, decreased during the first 5 h of reaction, reached a minimum, and then increased continuously until the 36 h termination. This behavior is consistent with an initial period in which, as the mass of SOA increases, products of higher volatility partition to the aerosol phase, followed by an aging period in which gas- and particle-phase reaction products become increasingly more oxidized. After about 12–13 h, the SOA mass reaches a maximum and decreases, suggesting the existence of fragmentation chemistry. When irradiation is stopped 12.4 h into one experiment, and OH generation ceases, no loss of SOA is observed, indicating that the loss of SOA is either light- or OH-induced. Chemical ionization mass spectrometry measurements of low-volatility m-xylene oxidation products exhibit behavior indicative of continuous photooxidation chemistry. A condensed chemical mechanism of m-xylene oxidation under low-NOx conditions is capable of reproducing the general behavior of gas-phase evolution observed here. Moreover, order of magnitude analysis of the mechanism suggests that gas-phase OH reaction of low volatility SOA precursors is the dominant pathway of aging in the m-xylene system although OH reaction with particle surfaces cannot be ruled out.

Comparing the fragmentation chemistry of gas-phase adducts of poly(dimethylsiloxane) oligomers with metal and organic ions

2009 ◽  
Vol 87 (2) ◽  
pp. 453-459 ◽  
Author(s):  
Justin Renaud ◽  
Abdulhrahman M. Alhazmi ◽  
Paul M. Mayer
Keyword(s):  
Gas Phase ◽  
Metal Ion ◽  
Secondary Ion Mass Spectrometry ◽  
Laboratory Frame ◽  
Fragment Ions ◽  
Gas Phase Ions ◽  
Fragmentation Chemistry ◽  
Secondary Ion ◽  
Cyclic Fragment ◽  
End Group

Gas-phase ions of poly(dimethylsiloxane) oligomers were formed by electrospray ionization either by protonating them in solution with formic acid or by generating adducts of the oligomers with the metal ions Li+, Na+, K+, and Ag+ as well as with the organic cations NH4+, CH3CH2NH3+, and protonated glycine, aspartic acid, and 1,2-diphenylethylamine. The collision-induced fragmentation of the oligomeric ions was strongly dependent on the nature of the charging species. Ag+ adducts dissociated in a manner previously observed in secondary ion mass spectrometry experiments generating a series of linear and cyclic fragment ions, while Li+ adducts fragmented to form two ions: an adduct of the metal ion with the oligomer end-group and one with the remaining oligomer. Na+ and K+ adducts simply dissociate to form the bare metal ion. The organic species, to varying extents, transfer the proton to the oligomer to form a protonated poly(siloxane) ion. These protonated oligomers then dissociate at very low laboratory-frame collision energy along the siloxane backbone by loss of a silanol. These backbone fragments can then lose a methyl group to form a second series of fragment ions. Suggestions for probable mechanistic pathways for these processes are presented.

scholarly journals Chemical aging of <i>m</i>-xylene secondary organic aerosol: laboratory chamber study

2012 ◽  
Vol 12 (1) ◽  
pp. 151-167 ◽  
Author(s):  
C. L. Loza ◽  
P. S. Chhabra ◽  
L. D. Yee ◽  
J. S. Craven ◽  
R. C. Flagan ◽  
...  
Keyword(s):  
Gas Phase ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Particle Phase ◽  
Particle Composition ◽  
Chemical Aging ◽  
Size Dependent ◽  
Volatile Products ◽  
Fragmentation Chemistry ◽  
Wall Loss

Abstract. Secondary organic aerosol (SOA) can reside in the atmosphere for a week or more. While its initial formation from the gas-phase oxidation of volatile organic compounds tends to take place in the first few hours after emission, SOA can continue to evolve chemically over its atmospheric lifetime. Simulating this chemical aging over an extended time in the laboratory has proven to be challenging. We present here a procedure for studying SOA aging in laboratory chambers that is applied to achieve 36 h of oxidation. The formation and evolution of SOA from the photooxidation of m-xylene under low-NOx conditions and in the presence of either neutral or acidic seed particles is studied. In SOA aging, increasing molecular functionalization leads to less volatile products and an increase in SOA mass, whereas gas- or particle-phase fragmentation chemistry results in more volatile products and a loss of SOA. The challenge is to discern from measured chamber variables the extent to which these processes are important for a given SOA system. In the experiments conducted, m-xylene SOA mass, calculated under the assumption of size-invariant particle composition, increased over the initial 12–13 h of photooxidation and decreased beyond that time, suggesting the existence of fragmentation chemistry. The oxidation of the SOA, as manifested in the O:C elemental ratio and fraction of organic ion detected at m/z 44 measured by the Aerodyne aerosol mass spectrometer, increased continuously starting after 5 h of irradiation until the 36 h termination. This behavior is consistent with an initial period in which, as the mass of SOA increases, products of higher volatility partition to the aerosol phase, followed by an aging period in which gas- and particle-phase reaction products become increasingly more oxidized. When irradiation is stopped 12.4 h into one experiment, and OH generation ceases, minimal loss of SOA is observed, indicating that the loss of SOA is either light- or OH-induced. Chemical ionization mass spectrometry measurements of low-volatility m-xylene oxidation products exhibit behavior indicative of continuous photooxidation chemistry. A condensed chemical mechanism of m-xylene oxidation under low-NOx conditions is capable of reproducing the general behavior of gas-phase evolution observed here. Moreover, order of magnitude analysis of the mechanism suggests that gas-phase OH reaction of low volatility SOA precursors is the dominant pathway of aging in the m-xylene system although OH reaction with particle surfaces cannot be ruled out. Finally, the effect of size-dependent particle composition and size-dependent particle wall loss rates on different particle wall loss correction methods is discussed.

scholarly journals Structure of olefin–imidacloprid and gas-phase fragmentation chemistry of its protonated form

2016 ◽  
Vol 14 (5) ◽  
pp. 1715-1726 ◽  
Author(s):  
Roberto Fusetto ◽  
Jonathan M. White ◽  
Craig A. Hutton ◽  
Richard A. J. O'Hair
Keyword(s):  
Gas Phase ◽  
Protonated Form ◽  
Fragmentation Chemistry ◽  
Fragmentation Reactions ◽  
Gas Phase Fragmentation

Gas-phase fragmentation reactions of protonated olefin–imidacloprid.

Cationized Carbohydrate Gas-Phase Fragmentation Chemistry

2016 ◽  
Vol 28 (4) ◽  
pp. 688-703 ◽  
Author(s):  
Benjamin J. Bythell ◽  
Maha T. Abutokaikah ◽  
Ashley R. Wagoner ◽  
Shanshan Guan ◽  
Jordan M. Rabus
Keyword(s):  
Gas Phase ◽  
Fragmentation Chemistry ◽  
Gas Phase Fragmentation

Sodium-cationized carbohydrate gas-phase fragmentation chemistry: influence of glycosidic linkage position

2017 ◽  
Vol 19 (37) ◽  
pp. 25643-25652 ◽  
Author(s):  
Jordan M. Rabus ◽  
Maha T. Abutokaikah ◽  
Reginald T. Ross ◽  
Benjamin J. Bythell
Keyword(s):  
Gas Phase ◽  
Phase Structure ◽  
Glycosidic Linkage ◽  
Linkage Position ◽  
Fragmentation Chemistry ◽  
Gas Phase Structure ◽  
Gas Phase Fragmentation

Gas-phase structure and fragmentation chemistries of isomeric sodium-cationized sugars.

Residual Gas Reactions in the Electron Microscope: I. Qualitative Observations on the Water Gas Reaction

1968 ◽  
Vol 26 ◽  
pp. 292-293
Author(s):  
Richard E. Hartman ◽  
Roberta S. Hartman ◽  
Peter L. Ramos
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Gas Phase ◽  
Absolute Temperature ◽  
Residual Gas ◽  
Gas Reactions ◽  
Image Position ◽  
The Right ◽  
Water Gas ◽  
Thinning Rate

The action of water and the electron beam on organic specimens in the electron microscope results in the removal of oxidizable material (primarily hydrogen and carbon) by reactions similar to the water gas reaction .which has the form:The energy required to force the reaction to the right is supplied by the interaction of the electron beam with the specimen.The mass of water striking the specimen is given by:where u = gH2O/cm2 sec, PH2O = partial pressure of water in Torr, & T = absolute temperature of the gas phase. If it is assumed that mass is removed from the specimen by a reaction approximated by (1) and that the specimen is uniformly thinned by the reaction, then the thinning rate in A/ min iswhere x = thickness of the specimen in A, t = time in minutes, & E = efficiency (the fraction of the water striking the specimen which reacts with it).

Integration of Core-Edge Spectroscopy Methods for the Study of Polymers

1996 ◽  
Vol 54 ◽  
pp. 154-155
Author(s):  
E. G. Rightor
Keyword(s):  
Excited State ◽  
Polymer Blends ◽  
Gas Phase ◽  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Electronic States ◽  
Core Electron ◽  
Bulk Solids ◽  
Development Application

Core edge spectroscopy methods are versatile tools for investigating a wide variety of materials. They can be used to probe the electronic states of materials in bulk solids, on surfaces, or in the gas phase. This family of methods involves promoting an inner shell (core) electron to an excited state and recording either the primary excitation or secondary decay of the excited state. The techniques are complimentary and have different strengths and limitations for studying challenging aspects of materials. The need to identify components in polymers or polymer blends at high spatial resolution has driven development, application, and integration of results from several of these methods.

Sign in / Sign up

Export Citation Format

Share Document