Spontaneous'' cluster decomposition in a quadrupole ion trap
- Oak Ridge National Lab., TN (USA)
- Tennessee Univ., Knoxville, TN (USA). Dept. of Chemistry
Cluster ions normally found in high pressure ion sources are not usually observed under chemical ionization conditions in the quadrupole ion trap. This is mainly due to the lower pressures in the ion trap which affect third body stabilization. But, even for cluster ions injected from an external source, decomposition is observed. By injecting cluster ions of known stability and measuring the decomposition rate as a function of pressure and time, we can determine what affects various parameters have on the internal ion temperatures in the quadrupole ion trap. The desolvation experiments were carried out by injecting ions formed via electrospray into the quadrupole ion trap. The atmospheric sampling glow discharge ionization (ASGDI) source served as the interface between atmosphere and the vacuum chamber. Protonated water clusters were formed by spraying distilled water at a flow rate of 1 uL/min and protonated methanol clusters were formed by spraying HPLC grade methanol at 1 uL/min. Since fragmentation of ions upon injection into an ion trap has been observed in our lab as well as others, we needed to determine if ions are excited'' during injection. Therefore, the cluster ion mass spectra from the ion trap was compared to the cluster ion mass spectra from a quadrupole mass filter using the same interface and electrospray conditions. The results showed that, under the ion injection conditions used in this study for both the water and methanol clusters, significant internal excitation did not occur during injection. The clusters, therefore, acquired the necessary energy for dissociation after they were trapped. 3 refs., 3 figs., 1 tab.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 5636056
- Report Number(s):
- CONF-9105181-4-Extd.Abst.; ON: DE91012519
- Country of Publication:
- United States
- Language:
- English
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