| Zugriffsnummer | 11331 |
| Dokumenttyp | Konferenzartikel in Zeitschrift |
| Sprache | Englisch |
| Titel | Hyperpolarized natural Xenon by spin-exchange optical pumping using Ti : sapphire and high-power diode lasers |
| Autor(in); Institution |
Kilian, Wolfgang; 8.12, Biomedizinische Optik und NMR-Messtechnik, PTB-Berlin
Grosenick, Dirk; 8.12, Biomedizinische Optik und NMR-Messtechnik, PTB-Berlin
Seifert, Frank; 8.12, Biomedizinische Optik und NMR-Messtechnik, PTB-Berlin
Rinneberg, Herbert; 8.12, Biomedizinische Optik und NMR-Messtechnik, PTB-Berlin
|
| Quelle/Jahr | European Radiology: 9 (1999), B11 |
| ISSN | 0938-7994 |
| Verlag | Berlin: Springer |
| Konferenzangaben | European Radiology; Hyperpolarized gases in magnetic resonance: biomedical investigations and clinical applications; International workshop: Les Houches, France, June 21-25, 1999, Le Houches, June 21-25, 1999, France |
| Freie Schlagworte | Hyperpolarized natural Xenon gas |
| Zusammenfassung | Objective of study: Comparison of Ti:Sapphire (Ti:Sa) and diode lasers as light sources in spin-exchange (SE) optical pumping of natural Xe. Methods used: As light sources we used a cw Ti:Sa laser (6 W @ 794.8 nm, bandwidth 8 GHz) or a high power diode laser (Coherent FAB-I, 30 W, linewidth 2-3 nm) temperature tuned (30 °C) to cover the D1 line of Rb vapor. The power incident on the pumping cell was about 5 W (Ti:Sa) or 12 W (diode laser). The temperature of the Rb-vapor cell (110°-130° C) was adjusted for about 60 % absorption of the Ti:Sa laser beam. The duran cell (30 cm3) was filled with 200 mbar N2, 200-500 mbar nat. Xe and a droplet of Rb. After optical pumping in a holding field of 10 mT the gas was expanded into an evaporated glass bulb. For absolute measurements (precision (15%) of the 129Xe hyperpolarization the in-house 3 T tomograph, a transmit/receive surface coil tuned to 34.66 MHz and the glass bulb with optically pumped nat. Xe were used. Initial amplitudes of the 129Xe FIDs were compared with the FID of thermally polarized nat. Xe. Results: Employing the Ti:Sa laser and a Xe pressure of 200 mbar we achieved up to 20 % polarization of 129Xe after 10 min of optical pumping. Nuclear spin polarization build-up times were measured to be 1-5 min. For the same experimental conditions, particularly for the same power absorbed, the Ti:Sa and diode lasers resulted in essentially the same nuclear spin polarization. Furthermore we achieved 10-15 % absorption of the diode laser radiation. Discussion: A rather large nuclear spin polarization of 129Xe can be achieved because of the surprisingly high absorption of the diode laser. The absorption considerably exceeds the ratio (2.5 %) of the width of the pressure broadened absorption line and the laser bandwidth. Conclusion: Because of the large saturated absorption of diode laser radiation even at total pressures p (1 bar such high power diode lasers are suitable for production of hyperpolarized nat. Xe by spin-exchange optical pumping. |
