Measurement of CO pressures in the ultrahigh vacuum regime using resonance‐enhanced multiphoton‐ionization time‐of‐flight mass spectroscopy
| Autor: | Thomas B. Lucatorto, Joel E. Harrington, Kermit C. Smyth, J. Patrick Looney, Thomas R. O'Brian |
|---|---|
| Rok vydání: | 1993 |
| Předmět: | |
| Zdroj: | Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films. 11:3111-3120 |
| ISSN: | 1520-8559 0734-2101 |
| DOI: | 10.1116/1.578306 |
| Popis: | An evaluation is made of measurements of CO pressures in the UHV regime using resonance‐enhanced multiphoton ionization coupled with time‐of‐flight mass spectroscopy (REMPI‐TOFMS). It has been found that once the REMPI‐TOFMS system has been calibrated, quantitative measurement of CO pressures as low as 10−10 Pa is possible, even in overwhelming N2 backgrounds. With compensation for laser pulse energy variations, we find measurements with uncertainties of 10%–15% are possible for pressures down to 10−7 Pa, and an ultimate detection limit for CO pressures of 10−10 Pa for our measurement system. In this study, the REMPI‐TOFMS system was calibrated using a pressure division technique along with a spinning rotor gage. The ionization of CO is achieved using 230 nm radiation to excite the B 1Σ+ state of CO at 10.8 eV via a two‐photon absorption and then ionizing some of the excited state molecules by the absorption of an additional photon from the laser beam. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|