Determination of bond dissociation energies using Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry

252 Pages·1996·6.2 MB·English

by  Yang, Yarjing

DETERMINATIONOFBONDDISSOCIATIONENERGIESUSINGFOURIER
TRANSFORMIONCYCLOTRONRESONANCE
(FT-ICR)MASSSPECTROMETRY
By
YARJINGYANG
ADISSERTATIONPRESENTEDTOTHEGRADUATESCHOOL
OFTHEUNIVERSITYOFFLORIDAINPARTIALFULFILLMENT
OFTHEREQUIREMENTSFORTHEDEGREEOF
DOCTOROFPHILOSOPHY
UNIVERSITYOFFLORIDA
1996
ACKNOWLEDGMENTS
Iwouldliketoexpressmyappreciationtomyresearchadvisor,Dr.JohnR.
Eyler, for his guidance and assistance, especially for his input of FT-ICR
background and theory. I also appreciate the technical knowledge of the
instrumentationprovidedbyDr.CliffWatson. IwouldliketothankDrs.DilPeiris
and Nathan Ramanathan for their efforts on the initial IRMPD work of the
metal/crownethercomplexes. Thecommentsandsuggestionsonmyresearch
projectsfromDr.PhilipBrucatandDr.DavidRichardsonarealsoacknowledged.
Myappreciationextendstomyparents;withouttheirloveandsupport, I
wouldneverbeabletofinishthiswork. Thankstoallofthemembers(RichBurton,
Kevin Goodner, Tom Hayes, David Kage, Lisa Lang, Eric Milgram, and Joe
Nawrocki)of thecurrentEylergroupfortheirassistanceandfriendship. Thanks
alsogotoDr.KittyWilliamsforherassistanceinthepreparationofresearchresults
forpublication.
Lastbutcertainlynotleast,Iwouldliketothankmydearhusband,Chen-
ChanHsueh,forhissupport,loveandhelp. Hehasbeensounderstandingand
helpfulduringmygraduatecareer. Withouthim, Iwouldnothavebeenableto
finishthegraduatestudies.
ii
TABLEOFCONTENTS
ACKNOWLEDGMENTS
jj
TABLEOFCONTENTS
jjj
LISTOFTABLES vi
LISTOFFIGURES vjj
ABSTRACT
xiii
CHAPTERS
1. INTRODUCTION 1
Fourier Transform Ion Cyclotron Resonance Mass
Spectrometry(FTICR-MS) 1
History 1
BasicConcepts 2
Ioncyclotronmotion 2
Ionexcitation 6
Iondetection 11
Signalacquisition 16
Applications 20
PurposeofThisWork 20
SolvatedAnions 24
Host-guestComplexes 26
MethodologyofDeterminationofBondDissociationEnergies 37
Photodetachment . 37
CAD 45
Energybehaviorofreactioncrosssection 45
On-resonanceCAD 47
Dopplerbroadening 49
Advantages,Disadvantages,andComparisonstoOther
Techniques 50
iii
Photodetachment 50
CAD 51
2. INSTRUMENTATION 53
Introduction 53
Nicolet2TeslaICRInstrument 56
Bruker7TeslaICRInstrument 66
ElectrosprayIonization(ESI)SourceRegion 71
IntroductionofESIFeatures 77
pKaorpKb 78
Concentration 78
Solubility 79
Molecularconformation 79
Molecularweight 80
Solventproperties 80
IonTransferRegion 81
IonAnalyzerregion 81
3. DETERMINATION OF BINDING ENERGIES OF
SINGLY-SOLVATED HALIDE IONS USING
PHOTODETACHMENT 88
Background 88
ExperimentalProceduresandDataAnalysis 92
ChemicalsandIon-MoleculeReactions 92
PulseSequence 109
DataAnalysis 109
ResultsandDiscussion 120
Conclusion 141
4. BOND DISSOCIATION ENERGIES OF ALKALI AND
HYDRONIUM CATIONS BOUND TO CROWN ETHERS
DETERMINED BY ON-RESONANCE COLLISIONALLY-
ACTIVATED DISSOCIATION(CAD) 144
Background 144
Experimental 150
Ionformation 150
Pulsesequence 154
DataAnalysis 155
IonAppearanceCurve 155
InternalEnergies 159
iv
Rotationalenergy 159
Vibrationalenergies 159
TrialFunction 160
Deconvolution 161
Results 163
CollisionConditions 163
FragmentationPathways 164
BondDissociationEnergies 197
Discussion 210
Conclusion 216
5. CONCLUSION 218
REFERENCELIST 223
BIOGRAPHICALSKETCH 235
v
LISTOFTABLES
Table page
1.1. Sizeofalkali-metalionsandcavitysizeofcrownethers 36
2.1. Laserdyesusedforphotodetachmentexperimentsandtheir
correspondingwavelengthrangebeforeandafterfrequency
doubling 68
3.1. Electron affinities (EA) and proton affinities (PA) ofspecies
studiedinthiswork 131
3.2. Photdetachmentthresholds(ET)andbindingenergies(BE's)of
solvatedhalides 133
4.1. Vibrationalfrequenciesofcyclohexaneand1,4-dioxane 152
4.2. Ionsobservedinmassspectra.Thecapillarypotentialwas25V
forionslabelledwithanasterisk,75Vforallotherions;(s)-
strongsignal,(w)-weaksignal 170
4.3. Bonddissociationenergiesforalkali-metalandhydroniumion
crownethercomplexesincludingpresentwork,previouswork,
andtheoreticallycalculatedvalues 209
vi
LISTOFFIGURES
Figure page
1.1. Standard ICRtrappingcells, (a)Cubiccellwithtwotrapping
platesperpendiculartoz-axis,twoexciteplatesperpendicular
tox-axis,andtwodetectplatesperpendiculartoy-axis.The
ionistrappedinsidethecellwithcyclotronmotioninthexy-
plane,movingalongthez-axis.(b)Cylindricalcell 5
1.2. StandardpulsesequenceforICRexperiment 8
1.3. Ionexcitation.(1)Impulseexcitation:approximatedeltafunction
vstime,Fouriertransformtothefrequencydomainsignal(2)
Chirp excitation: an rffrequency sweep vs time, Fourier
transformtothefrequencydomainsignal(3)SWIFT:(a)The
desiredfrequencyspectrum, (b) InverseFTtogiveatime-
domainsignal,(c)Fouriertransformtothefrequencydomain
signal 10
1.4. (1): (a) Ions'cyclotron motionpriortoexcitation, (b) Ionsare
excited to a larger orbit, (c) Ions achieve coherence after
excitation. (2) Phasecoherency: (a)Two ionsofsamem/z
180°outofphase,(b)Thein-phase(initialmotionparallelto
electricfield, E) ion speeds upand out-of-phase ion slows
downuntiltheyeventuallyachievecoherentmotion 13
1.5. Ions induce image current alternately on upper and lower
plates 15
1.6. Heterodynemode:Thesignalmixeswithareferencetogivea
sum (higher frequency) and difference (lower frequency)
signal.Thehigherfrequency(lowmass)signalisthenfiltered.
Fast FT gives the low frequency signal which is the
difference 19
1.7. ThestructuresofCH3OHX",X=F,CI,Br,and1 28
vii
1.8. Thestructuresofpolyethermacrocycles 30
1.9.Thestructuresofmetal/hydroniumion-crownethercomplexes... 33
1.10. Photodetachmentprocess:(a)A"+hv-A+e~,(b)A*+hv-B"
+C,(c)A"+hv-B+C+e" 40
2.1. SimplifiedblockdiagramofFTICRmassspectrometer 55
2.2. 2teslaICRinstrument(a)2Tmagnet,(b)Inletsource,(c)Three
window flange, (d) One window flange, (e) ICR cell, (f)
Diffusionpump,(g)Iongauge 58
2.3. Laser set-up for photodetachment experiment (1) Apple II
microcomputercontrols"charge"and"fire"commandsofYAG
laser, (2) Console sends external TTL pulsetotriggerthe
laser, (3)Powercontrolfromconsoletothecell; (a)Quartz
prism,(b)Laserquartzwindows,(c)ICRcell,(d)2Tmagnet,
(e)AppleIIcomputer,(f)Console,(g)Photodiode 60
2.4. Pulsesequenceforphotodetachmentexperiments 63
2.5. Cylindricalcell 65
2.6. 7TICRinstrument(a)7Tmagnet,(b)Infinity™cell,(c)400Us
cryopumps,(d)800L/scryopump,(e)Mechanicalpumps,(f)
Capillarycoatedwithplatinumatentranceandexitends,(g)
Needle,(h)Syringepump 70
2.7. IonformationinESI 73
2.8. ESIdesign 76
2.9. Electrostaticlensesintransferregion 83
2.10.Infinity™cellwiththree"side-kick"plates:(a)PVX1,(b)PVX3,
(c) PVX4 plates, (d) the macor platewhich is attached to
trapping plates to hold the "side-kick" plates and tra™pping
plates,(e)therf-shimmedtrappingplate,(f)theInfinity cell
withfourbrassplatesforexcitionanddetection 85
2.11. PulsesequenceforCADexperiments 87
viii
3.1. MassspectrumofF" 94
3.2. MassspectrumofCOCI" 96
3.3. Massspectrumof(CH3OH)F-,m/z=51 99
3.4. Massspectrumof(CH3OH)CI",m/z=67,69 101
3.5. MassspectrumofOH",m/z=17 104
3.6. Massspectrumof(H20)Br,m/z=97,99 106
3.7. Massspectrumof(CH3OH)Br,m/z=111,113 108
3.8. Photodetachmentspectrumof(C2H5OH)Br: -experimental
data; curve - best fit to the threshold region of
photodetachmenteffectvs.(E-ET)1/2-thearrowpointstothe
onsetthreshold 113
3.9. Photodetachmentspectrumof(CH3CN)Br: -experimental
data; curve - best fit to the threshold region of
photodetachmenteffectvs.(E-ET)1/2-thearrowpointstothe
onsetthreshold 115
3.10. Photodetachmentspectrum of(CH3OH)l": -experimental
data; curve - best fit to the threshold region of
photodetachmenteffectvs.(E-ET)1'2-thearrowpointstothe
onsetthreshold 117
3.11. Photodetachmentspectrumof(CH3OH)F": -experimental
data; curve - best fit to the threshold region of
photodetachmenteffectvs.(E-ET)1/2-thearrowpointstothe
onsetthreshold 119
3.12. Photodetachmentspectra: -(CH3CN)Br;•-(CH3OH)Br; -
(C2H5OH)Br; -(i-C3H7OH)Br;I-(n-C3H7OH)Br 122
3.13.Pthhoetromdaeltizaacthimoennttismpeesct(tr)a:of(-C1H=23O.H34)Fs"eocb;taXin-e1d=u3s.i2n0gsdeicff;erent-
t=3.77sec; I-1=4.31sec;•-1=6.05sec 124
3.14.Pdhioftfoerdeenttatchhemremnaltiszpaetciotnratoifme(sCH(t3):OH•)C-I"1=o2b.t0a5inseedc;using-
ix
t=3.20sec;B-t=4.34sec 126
3.15. dPihfofteroednetttahcehrmmaelnitzatsipoencttriamesof(t):(CH3-O1H=)2.B0r5soebct;aiAned-1=u3s.i7ng7
sec;•-1=4.34sec 128
3.16. Potential energy curvesforalcohol-solvated halideanions
and corresponding neutral species. The lower curve
representstheinteractionofthesolventandhalidefrominfinite
separationtoastableboundstate,a)Theuppersolidcurve
representsthehydrogenabstractionreactionofROH+Xto
form RO + HX. (X = F and CI). The arrows indicate the
thermochemical cycle for the photodetachment process,
includingthethreshold (Ethreshold),electronaffinity(EA)ofX,
bindingenergy(BE)of(ROH)X", andtheenergydifference
(AE)betweenthereportedandactualBE.b)Sameasa)with
dottedcurvetoindicatehydrogenabstractionreactionforX=
Brand1 136
4.1. Potential energy curve for ion crown ether complexes and
correspondingneutralspecies.TheD298representsthebond
dissociationenergyatroomtemperature,theD representsthe
bonddissociationenergyatzeroKelvintemperature 149
4.2. Appearance curve of(18-C-6)Rb+. The solid circles arethe
experimentaldata(meanoffivemeasurementswitherrorbars
correspondingto± 1standarddeviation);thecurveisthebest
fittothedatafromtheCRUNCHprogram 158
4.3. Appearancecurvesof(18-C-6)Rb+atdifferentpressures(50ms
CADdelaytime);T-3.0*10"8torr, -5.5*108torr,•-7.3
x10"8torr,A-9.2*10"8torr 166
4.4. Appearancecurvesof(18-C-6)Rb+atdifferentCADdelaytimes
(P=3.3x10"8torr);•-0.05s,A-0.08s, -0.1s, -0.15
s 168
4.5. Mass spectrum of (12-C-4)Rb+ at AV=20 volts. Peaks
corresponding to (12-C-4)Rb+ and (12-C-4)2Rb+ ions were
observed 173
4.6. Mcoarsrsespsopnedcitnrgutmo(o1f5-(C1-55-)CH-35)+H,3(1+5-Cat-5)A2VH=+2,a0ndvo(l1ts5.-C-Peaks
x