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Photoinitiated dynamics of cluster a...

Velarde, Luis Antonio.

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Photoinitiated dynamics of cluster anions via photoelectron imaging and photofragment mass spectrometry.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Photoinitiated dynamics of cluster anions via photoelectron imaging and photofragment mass spectrometry./
Author:	Velarde, Luis Antonio.
Description:	195 p.
Notes:	Adviser: Andrei M. Sanov.
Contained By:	Dissertation Abstracts International69-03B.
Subject:	Chemistry, Physical. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3303572
ISBN:	9780549501305

Photoinitiated dynamics of cluster anions via photoelectron imaging and photofragment mass spectrometry.
Velarde, Luis Antonio.

Photoinitiated dynamics of cluster anions via photoelectron imaging and photofragment mass spectrometry. - 195 p.

Adviser: Andrei M. Sanov.

Thesis (Ph.D.)--The University of Arizona, 2008.

Mass-selected cluster anions are employed as model micro-solutions to study solvent effects on the structural motifs and electronic structure of anionic solutes, including the roles of the solvent in controlling the outcomes of photochemical processes. Interaction of light with cluster anions can potentially lead to cluster photodissociation in addition to photodetachment. We investigate these competing processes by means of photoelectron imaging spectroscopy combined with tandem time-of-flight (TOF) mass spectrometry. Photoelectron images are reported for members of the [(CO2)n(H 2O)m]- cluster series. For homogeneous solvation, the photodetachment bands show evidence of cluster core switching between a co-2 monomer anion and a covalent ( &parl0;co2&parr0;-2 ) dimer anionic core, confirming previous observations. The Photoelectron Angular Distributions (PADs) of the monomer- and dimer-based clusters reveal an interference effect that result in similar PADs. Stabilization of the metastable co-2 anion by water solvent molecules is highlighted because its ability to "trap" the excess electron on CO2. Most surprising is the effect of the water solvent in quenching the autodetachment channel in excited states normally embedded in the electron detachment continuum, allowing excited co-2 (H2O)m clusters to follow reaction paths that lead to cluster fragmentation. Observed O-(H 2O)m-k based photoproducts are attributed to photodissociation of the CO2- cluster core and are dominant for small parent clusters, whereas a water evaporation channel dominates for larger clusters. Addition of a second CO2 to these clusters is shown to preferentially form monomer based clusters, whose photodissociation exhibit an additional co-3 based channel, characteristic of a photoinitiated intracluster ion-molecule reaction between nascent O- and the additional CO2 solvent molecule. Changes in the PADs of NO- are monitored as a function of electron kinetic energy for the NO-(N 2O)n and NO-(H2O) n cluster anions. In contrast with hydration, angular distributions become progressively more isotropic for the N2O case, particularly when the photoelectron kinetic energies are in the vicinity of the 2pi shape resonance of the N2O solvent molecules. First time observation of the CH3SOCH- anion of dimethylsulfoxide is reported along with the photoelectron images of this organic anion and of the monohydrated cluster. Observed photodissociation products are HCSO - and SO-.

ISBN: 9780549501305Subjects--Topical Terms:

560527
Chemistry, Physical.

Photoinitiated dynamics of cluster anions via photoelectron imaging and photofragment mass spectrometry.
LDR:03403nam 2200277 a 45 001 962523
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020 $a 9780549501305
035 $a (UMI)AAI3303572
035 $a AAI3303572
040 $a UMI $c UMI
100 1 $a Velarde, Luis Antonio. $3 1285582
245 1 0 $a Photoinitiated dynamics of cluster anions via photoelectron imaging and photofragment mass spectrometry.
300 $a 195 p.
500 $a Adviser: Andrei M. Sanov.
500 $a Source: Dissertation Abstracts International, Volume: 69-03, Section: B, page: 1674.
502 $a Thesis (Ph.D.)--The University of Arizona, 2008.
520 $a Mass-selected cluster anions are employed as model micro-solutions to study solvent effects on the structural motifs and electronic structure of anionic solutes, including the roles of the solvent in controlling the outcomes of photochemical processes. Interaction of light with cluster anions can potentially lead to cluster photodissociation in addition to photodetachment. We investigate these competing processes by means of photoelectron imaging spectroscopy combined with tandem time-of-flight (TOF) mass spectrometry. Photoelectron images are reported for members of the [(CO2)n(H 2O)m]- cluster series. For homogeneous solvation, the photodetachment bands show evidence of cluster core switching between a co-2 monomer anion and a covalent ( &parl0;co2&parr0;-2 ) dimer anionic core, confirming previous observations. The Photoelectron Angular Distributions (PADs) of the monomer- and dimer-based clusters reveal an interference effect that result in similar PADs. Stabilization of the metastable co-2 anion by water solvent molecules is highlighted because its ability to "trap" the excess electron on CO2. Most surprising is the effect of the water solvent in quenching the autodetachment channel in excited states normally embedded in the electron detachment continuum, allowing excited co-2 (H2O)m clusters to follow reaction paths that lead to cluster fragmentation. Observed O-(H 2O)m-k based photoproducts are attributed to photodissociation of the CO2- cluster core and are dominant for small parent clusters, whereas a water evaporation channel dominates for larger clusters. Addition of a second CO2 to these clusters is shown to preferentially form monomer based clusters, whose photodissociation exhibit an additional co-3 based channel, characteristic of a photoinitiated intracluster ion-molecule reaction between nascent O- and the additional CO2 solvent molecule. Changes in the PADs of NO- are monitored as a function of electron kinetic energy for the NO-(N 2O)n and NO-(H2O) n cluster anions. In contrast with hydration, angular distributions become progressively more isotropic for the N2O case, particularly when the photoelectron kinetic energies are in the vicinity of the 2pi shape resonance of the N2O solvent molecules. First time observation of the CH3SOCH- anion of dimethylsulfoxide is reported along with the photoelectron images of this organic anion and of the monohydrated cluster. Observed photodissociation products are HCSO - and SO-.
590 $a School code: 0009.
650 4 $a Chemistry, Physical. $3 560527
650 4 $a Physics, Molecular. $3 1018648
690 $a 0494
690 $a 0609
710 2 $a The University of Arizona. $b Chemistry. $3 1035937
773 0 $t Dissertation Abstracts International $g 69-03B.
790 $a 0009
790 1 0 $a Sanov, Andrei M., $e advisor
791 $a Ph.D.
792 $a 2008
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3303572