Transcript Nathan_Roehr_MG13_Final.pptx

UV/Vis Absorption Experiments on
Mass Selected Cations by CounterIon Introduction in an Inert Neon
Matrix
Nathan Roehr
University of Florida
67th International Symposium on
Molecular Spectroscopy
Thanks
University of Florida
 Dr. Nick Polfer
 Dr. Martin Vala
 Dr. Jan Szczepanski
 Dr. John Eyler
 Polfer and Eyler Group
 Ardara Technologies – Randy Pedder
 Machine and Electronic Shop
 Physical Chemistry Travel Grant
 ACS PRF #49572-‐DNI6
Lehigh University
 Dr. David Moore
 Ryan Ludwig
 Alex Hunter
 Moore Group Members
 67th Ohio State Symposium of Molecular Spectroscopy
Outline
Matrix Isolation of Mass-Selected Ions
Counter-Ion Introduction
UF Instrument
CO+ and SF6- Results
Lehigh instrument
Cu- and Ar+/Kr+ Results
Summary
Experimental Set-Up for Matrix Isolation
Expts on Mass-Selected Cations
 Source of Ionization
 Mass Analyzer or Mass Filter
 Electrostatic/Electrodynamic Ion
Guides
 Cold Cryostat Target
Inlet for
Neutral
(+)
Electron
Filament
(EI Source)
2
(-)
(-)
Einzel A
Inert Gas Inlet
Cold (4-20K)
Cryostat Target
Einzel C
Quadrupole
Mass Filter
Einzel B
1-2 hrs
nA of Ion Current
90 or 270 deg
Ion Bender
4
Other Modifications
Inert Gas Inlet
Counter Ions
+
z
+
And Scavenger x
+
 Originally Neglected
Cryostat Target
hu
CS2+
Cl-
hu
 Cold Metal Bombardment
 Inconsistent
 Unknown Counter-Ions
 Throwing Away Ions
 Electron gun
 Only Works for Cations
 Use of Scavenger
 Atomic or Molecular
Counter Ions

Leroi, G. et al ,Soc. for Applied Spec. 15, 4 (1991).
It didn’t work
5
Cryostat Window
UF Instrument
Quadrupole
Mass Filter
SF6
Deflector
CO
EI Source
• ~5 nA of both CO+
and SF6- ions
• 10 V bias
• 12 hrs of Deposition
CI Source
IR Spectra - CO+ and SF6- Deposition
Absorbance
2137.7 cm-1
νa CO
CO+
Gas - 2183.9 cm-1
Solid Neon – 2194.4 cm-1
2148.8 cm-1
νm CO
?
Wavenumber / cm-1
Jacox, M.E. , Chem. Phys. 189, (1994). 149-170
Lehigh University
David Moore
Assistant Professor
Ryan Ludwig
Grad Student
Alex Hunter
Masters Student
UV-Vis CCD
Detector
KBr Window
20K or 15K Ar
Lehigh Instrument
Octopole
Ion Guide
UV-Vis
Source
Quadrupole
Mass Filter
Quadrupole
Ion Guide
Magnetron
EI Source
Ar or Kr
Deflector
• ~3-5 nA of both Cuand Ar+ or Kr+ ions
• 10 V bias
• 3 hrs of Deposition
Aggregation
Region
Cu Target
UV Spectra Cu- and Ar+ Deposition
05/28
20K
304.22
308.99
(4p)2P <- (4s)2S
299, 302, 306
300.18
Absorbance
319.9
323.66
05/25
λ / nm
20K
λ / nm
Ozin, G.A. et al , J. Phys. Chem. 86, 473-479 (1982).
Literature Cu Neutral:
Thermally Unstable 319, 323
UV Spectra Comparison
05/25
05/28
20K
10K
Absorbance
Absorbance
10K
20K
32K
λ / nm
32K
λ / nm
UV Spectra Cu- and Ar+ Deposition
20K
Absorbance
26K
32K
50K
100K
300K
Akilbekov, A.T. et al , Fiz. Tverd, Tela, 86, 473-479 (1982).
λ / nm
UV Spectra Cu- and Kr+ Deposition
Absorbance
0.14” Lower
Center
15K
λ / nm0.14” Higher
λ / nm
Summary & Conclusions
Detectable Quantities of Neutral Species
Trapped in Solid Argon
Deposition Occurred Mostly at the Beam
Center
Temperature Affected Ratio of Thermally
Unstable Bands
Further Work
Deposit Neutral Cu to Check Peak Ratio at
~309-310 nm
Deposit Cu2- into Matrix
Introduce O2 or CO with Matrix Gas to See if
Metal Ligand Complexes Form
Deposit Cu+ to Determine Cation/Neutral
Ratio
END
UF Setup