1. Molecular Lightning Rods: Charge Steering during Ionization of the Isomers of HCCCN-HCN and HCCH-HCN in Helium Nanodroplets
William K. Lewis, C. Michael Lindsay and Roger E. Miller
Department of Chemistry
University of North Carolina at Chapel Hill

2. Ionization Methods Electron impact Photoionization Chemical ionization
Field Ionization
MALDI
Electrospray + +

3. Ionization Methods Electron impact Photoionization Chemical ionization
Field Ionization
MALDI
Electrospray
K. Joutsiniemi,et al., Rapid Commun. Mass Spectrom., 12, 876 (1998).
F. Remacle, et al., J. Phys. Chem. A, 103, (1999).
W. C. Stolte, et al., J. Phys. B: At. Mol. Opt. Phys., 35, L253 (2002).
M. Thevis, et al., J. Am. Soc. Mass Spectrom. 14, 658 (2003).
A. F. Lago, et al., J. Chem. Phys. 120, 9547 (2004).

4. Charge Transfer Ionization in Helium Droplets
Helium atom is ionized by e- impact
Charge begins to migrate through the droplet on the femtosecond timescale
He+ + n He  He+n+1
He+n+1 is desolvated
Charge transfers to dopant and vibrationally hot ion evaporates the droplet. +
work of Toennies, Janda, Atkins, Halberstadt, and others

5. + - + +
Lewis, et al, J. Am. Chem. Soc., 127, 7235 (2005)

6. Steering Charges with Electrostatic Moments+ -
IPHe-IPmolecule=10-15 eV
T=0.4 K, 1016 K/s cooling rate + -

7. Steering Charges with Electrostatic Moments+ -
IPHe-IPmolecule=10-15 eV
T=0.4 K, 1016 K/s cooling rate + -

8. Optically Selected Mass Spectrometry (OSMS)
e- impact
quadrupole mass spectrometer

9. Optically Selected Mass Spectrometry (OSMS)
e- impact
quadrupole mass spectrometer hv

10. Optically Selected Mass Spectrometry (OSMS)
e- impact
quadrupole mass spectrometer hv

11. HCCH  HCCH+
HCN + HCCH+  HCN-H+ + CCH ΔH = -0.4 eV
HCN  HCN+
HCCH + HCN+  HCCH-H+ + CN ΔH = -1.3 eV
HCCH + HCN+  HCCH+ + HCN ΔH = -2.2 eV
HCN+  H + CN ΔH = 5.4 eV
J. Francisco and S. Richardson, JCP, 101, 7707 (1994)., NIST Webbook, CRC Handbook

12. + - + - 3259 cm-1 3235 cm-1 HCN  HCN+
HCCCN + HCN+  HCCCN-H+ + CN ΔH = -2.4 eV
HCCCN + HCN+  HCCCN+ + HCN ΔH = -2.0 eV
3259 cm-1
3235 cm-1
HCCCN  HCCCN+
HCN + HCCCN+  HCN-H+ + CCCN ΔH = 0.9 eV
J. Francisco and S. Richardson, JCP, 101, 7707 (1994)., NIST Webbook, CRC Handbook

13. Unfavored product ions[ ]+
 HCCCN-H+
HCCCN+ + HCN  HCCCN-H+ + CN ΔE = -0.4 eV
HCCCN + HCN+  HCCCN-H+ + CN ΔE = -2.4 eV [ ]+
 HCN-H+
HCN+ + HCCCN  HCN-H+ + CCCN ΔE = -1.0 eV
HCN + HCCCN+  HCN-H+ + CCCN ΔE = 0.9 eV

14. Unfavored product ions[ ]+
 HCN-H+
HCN+ + HCCH  HCN-H+ + CCH ΔE = -2.5 eV
HCN + HCCH+  HCN-H+ + CCH ΔE = -0.4 eV [ ]+
 HCCH-H+
HCCH+ + HCN  HCCH-H+ + CN ΔE = 0.9 eV
HCCH + HCN+  HCCH-H+ + CN ΔE = -1.3 eV

15. Summary
OSMS spectra have been used to examine the ions formed from various isomers of HCN-HCCH and HCN-HCCCN.
The ions observed are consistent with charge steering by the electrostatic moments of the complex.
Product ions requiring large amplitude rearrangements are not observed (or only weakly present), suggests rapid cooling and/or caging.

16. Acknowledgements Jeremy Merritt Paul Stiles Gary Douberly
Myong-Yong Choi
Travis Falconer
Mike Barrett
Alessandra Ferzoco
Phil Remes
Aaron Johnson