Name: molecular beam mass spectrometry with tunable vacuum ultraviolet (vuv) synchrotron radiation
Uploaded: 2012-10-30T14:00:00
Description: Watch this Scientific Journal Video about Molecular Beam Mass Spectrometry With Tunable Vacuum Ultraviolet VUV Synchrotron Radiation at JoVE.com

Forsøgene blev udført ved Chemical Dynamics beamline på Advanced Light Source, Lawrence Berkeley National Laboratory og støttet af Office of Science, Office of Basic Energi Videnskaber, af det amerikanske Department of Energy under kontrakt nr. DE-AC02-05CH11231, gennem Chemical Sciences Division.

1. Prøve Loading <ol><li> Fjern bagflange og adskille 3/8 &quot;rustfri dyse rør fra apparatet (se figur 1 og figur 2) og sørg for at det er ren og 100 mm åbning er klart (Dette kan gøres ved at se på en lyskilde gennem det). Til rengøring, fylde røret med ~ 1 ml ethanol og krat indefra med bomuld tips. Alternativt, skal du placere dysen i et ultralydsbad fyldt med sæbe og vand eller ethanol til omkring 20 min. Tør efter med trykluft. </li><li> Ved hjælp af en lille, ren sp...

<ol>
	<li>Golan, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ionization+of+dimethyluracil+dimers+leads+to+facile+proton+transfer+in+the+absence+of+hydrogen+bonds.">Ionization of dimethyluracil dimers leads to facile proton transfer in the absence of hydrogen bonds.</a> Nat. Chem. 4, 323-329 (2012).</li><li>Belau, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vacuum-Ultraviolet+Photoionization+Studies+of+the+Microhydration+of+DNA+Bases+(Guanine,+Cytosine,+Adenine,+and+Thymine).">Vacuum-Ultraviolet Photoionization Studies of the Microhydration of DNA Bases (Guanine, Cytosine, Adenine, and Thymine).</a> The Journal of Physical Chemistry A. 111, 7562-7568 (2007).</li><li>Golan, A., Ahmed, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ionization+of+Water+Clusters+Mediated+by+Exciton+Energy+Transfer+from+Argon+Clusters.">Ionization of Water Clusters Mediated by Exciton Energy Transfer from Argon Clusters.</a> The Journal of Physical Chemistry Letters. 3, 458-462 (2012).</li><li>Nicolas, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Vacuum+Ultraviolet+Photoionization+of+C3.">Vacuum Ultraviolet Photoionization of C3.</a> Journal of the American Chemical Society. 128, 220-226 (2005).</li><li>Kamarchik, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spectroscopic+signatures+of+proton+transfer+dynamics+in+the+water+dimer+cation.">Spectroscopic signatures of proton transfer dynamics in the water dimer cation.</a> Journal of Chemical Physics. 132, (2010).</li><li>Khistyaev, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+microhydration+on+ionization+energies+of+thymine.">The effect of microhydration on ionization energies of thymine.</a> Faraday Discussions. 150, 313-330 (2011).</li><li>Bravaya, K. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+effect+of+pi-stacking,+H-bonding,+and+electrostatic+interactions+on+the+ionization+energies+of+nucleic+acid+bases:+adenine-adenine,+thymine-thymine+and+adenine-thymine+dimers.">The effect of pi-stacking, H-bonding, and electrostatic interactions on the ionization energies of nucleic acid bases: adenine-adenine, thymine-thymine and adenine-thymine dimers.</a> Physical Chemistry Chemical Physics. 12, 2292-2307 (2010).</li><li>Kostko, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ionization+of+cytosine+monomer+and+dimer+studied+by+VUV+photoionization+and+electronic+structure+calculations.">Ionization of cytosine monomer and dimer studied by VUV photoionization and electronic structure calculations.</a> Physical Chemistry Chemical Physics. 12, 2860-2872 (2010).</li><li>Bravaya, K. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Electronic+Structure+and+Spectroscopy+of+Nucleic+Acid+Bases:+Ionization+Energies,+Ionization-Induced+Structural+Changes,+and+Photoelectron+Spectra.">Electronic Structure and Spectroscopy of Nucleic Acid Bases: Ionization Energies, Ionization-Induced Structural Changes, and Photoelectron Spectra.</a> Journal of Physical Chemistry A. 114, 12305-12317 (2010).</li><li>Leone, S. R., Ahmed, M., Wilson, K. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+dynamics,+molecular+energetics,+and+kinetics+at+the+synchrotron.">Chemical dynamics, molecular energetics, and kinetics at the synchrotron.</a> Physical Chemistry Chemical Physics. 12, 6564-6578 (2010).</li><li>Scoles, G., Bassi, D., Buck, U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Atomic and Molecular Beam Methods. 1, (1988).</li><li>Pauly, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Atom, Molecule and Cluster Beams I. , (2000).</li><li>Wiley, W. C., McLaren, I. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Time-of-Flight+Mass+Spectrometer+with+Improved+Resolution.">Time-of-Flight Mass Spectrometer with Improved Resolution.</a> Review of Scientific Instruments. 26, 1150-1157 (1955).</li><li>Levy, D. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Spectroscopy+of+Very+Cold+Gases.">The Spectroscopy of Very Cold Gases.</a> Science. 214, 263-269 (1981).</li></ol>

De monomerer og dimerer dannes i en supersonisk stråle ekspansion, som giver anledning til en molekylær stråle. En lille prøve af DNA basen er placeret i et termisk fordampning kilde og opvarmedes til at generere tilstrækkeligt damptryk. Argongas bærer dampe gennem en 100 um dyse og passerer en 2 mm skimmer at frembringe en kold molekylær stråle 14. Alternativt kan et effusive strålen anvendes, hvor prøven anbringes i en opvarmet ovn fastgjort til repeller pladen (ion optik) i massespektrometret. </...

<table border="1"&gt;<tr&gt;<td<strong&gt; Navn på reagens / Material</strong</td&gt;<td<strong&gt; Firma</strong</td&gt;<td<strong&gt; Catalog Number</strong</td&gt;<td<strong&gt; Kommentarer</strong</td&gt;</tr&gt;<tr&gt;<td&gt; Uracil</td&gt;<td&gt; Sigma</td&gt;<td&gt; U0750</td&gt;<td</td&gt;</tr&gt;<tr&gt;<td&gt; 1,3-dimethyluracil</td&gt;<td&gt; Aldrich</td&gt;<td&gt; 349.801</td&gt;<td</td&gt;</tr&gt;</table

molecular beam mass spectrometry with tunable vacuum ultraviolet (vuv) synchrotron radiation

Afstemmelige blød ionisering koblet til massespektroskopi er en kraftfuld metode til at undersøge isolerede molekyler, komplekser og klynger og deres spektroskopi og dynamik 1-4. Grundlæggende studier af photoionization processer biomolekyler giver oplysninger om den elektroniske struktur af disse systemer. Endvidere bestemmelser af ioniseringsenergier og andre egenskaber af biomolekyler i gasfasen er ikke triviel, og disse forsøg giver en platform til at generere disse data. Vi har udviklet en termisk fordampning teknik kombineret med supersoniske molekylære stråler, der giver en skånsom måde at transportere disse arter til gasfasen. Fornuftig kombination af kilden for gas og temperatur muliggør dannelsen af ​​dimerer og højere klynger af DNA-baser. Fokus for netop dette værk er om virkningerne af ikke-kovalente interaktioner, dvs, hydrogenbinding, stabling, og elektrostatiske interaktioner, på ioniseringsenergier ogprotonoverførsel af individuelle biomolekyler, deres komplekser og efter mikro-hydrering af vand 1, 5-9. Vi har udført eksperimentelle og teoretiske karakterisering af photoionization dynamik gasfase-uracil og 1,3-dimethyluracil dimerer ved hjælp af molekylære stråler kombineret med synkrotronstråling på Chemical Dynamics beamline 10 placeret på Advanced Light Source og de ​​eksperimentelle detaljer er visualiseret her. Dette tillod os at observere protonoverførsel i 1,3-dimethyluracil-dimerer, et system med pi stacking geometri og uden hydrogenbindinger 1. Molekylære stråler giver en meget bekvem og effektiv måde at isolere prøven af interesse fra miljømæssige forstyrrelser, som til gengæld giver nøjagtig sammenligning med elektroniske struktur beregninger 11, 12. Ved tuning foton energi fra synkrotron, en photoionization effektivitet (PIE) kurve kan plottes som informerer os om det kationiskeelektroniske tilstande. Disse værdier kan derefter sammenlignes med teoretiske modeller og beregninger og til gengæld i detaljer forklare den elektroniske struktur og dynamik af de undersøgte arter 1, 3.

7 viser et typisk massespektrum af den supersoniske ekspansion af 1,3-dimethyluracil dampe (A) og kagen kurverne for de tre hovedtræk (monomeren ved m / z 140, protoneret monomer ved m / z 141, og en ,3-dimethyluracil dimer ved m / z 280), som ekstraheres fra en VUV scanning mellem 8 eV og 10 eV (B). Den grå skygge er standardafvigelsen fra tre på hinanden følgende skanninger. <img alt="Figur 1" fo:content-width="5in" fo:src="/files/f...

Watch this Scientific Journal Video about Molecular Beam Mass Spectrometry With Tunable Vacuum Ultraviolet VUV Synchrotron Radiation at JoVE.com

Molecular Beam Mass Spectrometry With Tunable Vacuum Ultraviolet VUV Synchrotron Radiation

En molekylær stråle koblet til afstemmelige vakuum ultraviolet photoionization massespektrometer ved en synkrotron giver et praktisk værktøj til at udforske den elektroniske struktur af isolerede gasfase molekyler og klynger. Protonoverførsel mekanismer i DNA-base-dimerer blev belyst med denne teknik.

Molekylær Beam massespektrometri Med Tunable Vacuum Ultraviolet (VUV) synkrotronstråling

Tunable soft ionization coupled to mass spectroscopy is a powerful method to investigate isolated molecules, complexes and clusters and their spectroscopy ...

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Molecular Beam Mass Spectrometry With Tunable Vacuum Ultraviolet (VUV) Synchrotron Radiation

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