Single photon ionization of hydrogen bonded clusters with a soft x-ray laser: (HCOOH){sub x} and (HCOOH){sub y}(H{sub 2}O){sub z}
Pure, neutral formic acid (HCOOH){sub n+1} clusters and mixed (HCOOH)/(H{sub 2}O) clusters are investigated employing time of flight mass spectroscopy and single photon ionization at 26.5 eV using a very compact, capillary discharge, soft x-ray laser. During the ionization process, neutral clusters...
Saved in:
Published in: | The Journal of chemical physics 2007-06, Vol.126 (24) |
---|---|
Main Authors: | , , , , , , , |
Format: | Article |
Language: | eng |
Subjects: | |
Online Access: | Get full text |
Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
Summary: | Pure, neutral formic acid (HCOOH){sub n+1} clusters and mixed (HCOOH)/(H{sub 2}O) clusters are investigated employing time of flight mass spectroscopy and single photon ionization at 26.5 eV using a very compact, capillary discharge, soft x-ray laser. During the ionization process, neutral clusters suffer little fragmentation because almost all excess energy above the vertical ionization energy is taken away by the photoelectron, leaving only a small part of the photon energy deposited into the (HCOOH){sub n+1}{sup +} cluster. The vertical ionization energy minus the adiabatic ionization energy is enough excess energy in the clusters to surmount the proton transfer energy barrier and induce the reaction (HCOOH){sub n+1}{sup +}{yields}(HCOOH){sub n}H{sup +}+HCOO making the protonated (HCOOH){sub n}H{sup +} series dominant in all data obtained. The distribution of pure (HCOOH){sub n}H{sup +} clusters is dependent on experimental conditions. Under certain conditions, a magic number is found at n=5. Metastable dissociation rate constants of (HCOOH){sub n}H{sup +} are measured in the range (0.1-0.8)x10{sup 4} s{sup -1} for cluster sizes 4 |
---|---|
ISSN: | 0021-9606 1089-7690 |