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Electron-stimulated desorption from partially fluorinated hydrocarbon thin films: Molecules with common versus separate hydrogen and fluorine bonding sites

Journal Article · · Phys. Rev. B: Condens. Matter; (United States)
We have observed H/sup +/ and F/sup +/ yields as a function of low-energy (10--100 eV) electron bombardment from thin films of solid nonafluoroisobutane ((CF/sub 3/)/sub 3/CH), 1,2,3,5-tetrafluorobenzene (C/sub 6/H/sub 2/F/sub 4/), 1-fluorobutane (C/sub 4/H/sub 9/F), and fluorocyclohexane (C/sub 6/H/sub 11/F). For the materials with separate H and F bonding sites (C/sub 6/H/sub 2/F/sub 4/ and (CF/sub 3/)/sub 3/CH), H/sup +/ and F/sup +/ have different appearance potentials, corresponding, respectively, to excitations of the C 2s and F 2s levels (approx.25 and approx.40 eV). For the materials with common H and F bonding sites, the H/sup +/ and F/sup +/ appearance potentials correspond to excitation of the C 2s level. The F/sup +/ threshold is relatively weak, and a steep increase in the F/sup +/ yield is observed near 40 eV (F 2S excitation). These results indicate that the final-state excitations leading to ion desorption in these systems are localized within functional groups but not necessarily within individual C--H or C--F bonds of the functional group.
Research Organization:
Sandia National Laboratories, Albuquerque, New Mexico 87185
DOE Contract Number:
AC04-76DP00789
OSTI ID:
6457376
Journal Information:
Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 30:1; ISSN PRBMD
Country of Publication:
United States
Language:
English