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In this paper, we obtain the rotational constant and the distortion constant of v=187 belonging to 0u+ state below the 6S1/2+6P1/2 disassociation limit. In our experiment, we first prepare the ultra-cold cesium sample in the MOT (magneto-optical trap) by six beams of pumping laser, one beam of repumping laser, and a pair of anti-Helmholtz coils. Then we construct a high-resolution frequency reference using the double-pass photoassociation technique. The double-pass photoassociation technique is a creative and robust method. We use a polarization beam splitter to split one laser beam from the laser to two beams-Laser Ⅰ and Laser Ⅱ; Laser Ⅱ then passes twice through an acousto-optic modulator (AOM) whose central frequency is 110 MHz, using a reflecting mirror and a convex lens before illuminating the MOT. We use two shutters-S1 and S2 to control Laser Ⅰ and Laser Ⅱ. Open S1 while keep S2 close to make Laser I interact with the MOT; and after the rotational spectroscopy of J=0-6 is observed, turn off S1 and turn on S2 immediately. Let laser II interact with MOT and obtain another part of spectroscopy that is exactly the same with J=6; we define this part of spectroscopy as J'=6. The frequency interval between J=6 and J'=6 is exactly 220 MHz for the scan process is strictly linear, and that can be an accurate frequency interval in our experiment. The laser intensities of these two laser beams have to be strictly equal in case of the laser-induced frequency shift. Using the frequency interval of 220 MHz, we can calculate the frequency interval of J=0-6. The detection method we used here is the trap loss spectroscopic technology by modulating fluorescence of cold atoms in the MOT, which allows a direct spectroscopy detection at the rovibrational levels for a very weak transition probability. With the frequency intervals of each rotational quantum number, we can fit the frequency intervals to the non-rigid model to derive the rotation constant B and distortion constant D which are crucial to precisely measure the full molecule potential curves as well as deepen our understanding of molecular formation. This kind of double-pass photoassociation technique not only can direct obtain the precise value of rotation constant B and distortion constant D as compared with the traditional photoassociation method, but also can obtain a relatively accurate potential energy curve. And another great advantage is that we are able to calculate the frequency intervals easily without the wavelength meter which is rather expensive and difficult to control.
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Keywords:
- ultra-cold molecules /
- rotational spectroscopy /
- rotational constant /
- double-pass photoassociation technique
[1] Kajita M 2004 Phys. Rev. A 69 012709
[2] Jochim S, Bartenstein M, Altmeyer A, Hendl G, Chin C, Hecker Denschlag J, Grimm R 2003 Phys. Rev. Lett. 91 240402
[3] Wynar R, Freeland R S, Han D J, Ryu C, Heinzen D J 2000 Science 287 1016
[4] Pillet R, Drag C, Tolra B L 2001 Laser Phys. 11 480
[5] Tsai C, Freeland R, Vogels J, Boesten H 1997 Phys. Rev. Lett. 79 1245
[6] Wang J M 1999 Ph. D. Dissertation (Taiyuan: Shanxi University) (in Chinese) [王军民 1999 博士学位论文 (太原: 山西大学)]
[7] Jones K M, Tiesinga E, Lett P D, Julienne P S 2006 Rev. Mod. Phys. 78 483
[8] Jiang K J, Li K, Wang J, Zhan M S 2006 Acta Phys. Sin. 55 125 (in Chinese) [江开军, 李可, 王瑾, 詹明生 2006 物理学报 55 125]
[9] Zhang Y C, Wu J Z, Ma J, Zhao Y T, Wang L R, Xiao L T, Jia S T 2010 Acta Phys. Sin. 59 5418 (in Chinese) [张一驰, 武寄洲, 马杰, 赵延霆, 汪丽蓉, 肖连团, 贾锁堂 2010 物理学报 59 5418]
[10] Zhang W, Huang Y, Xie T, Wang G R, Cong S L 2010 Phys Rev. A 82 063411
[11] Fioretti A, Comparat D, Drag C, Amiot C, Dulieu O, Masnou-Seeuws F, Pillet P 1999 Eur. Phys. J. D 5 389
[12] Fioretti A, Comparat D, Drag C, Amiot C, Dulieu O, Masnou-Seeuws F, Pillet P 1998 Phys. Rev. Lett. 80 4402
[13] Comparat D, Drag C, Fioretti A, Dulieu O, Pillet P 1999 J. Mol. Spectrosc. 195 229
[14] Pichler M, Chen H, Stwalley W C 2004 J. Chem. Phys. 121 6779
[15] Ma J, Wang L R, Zhao Y T, Xiao L T, Jia S 2009 J. Mol. Spectrosc. 255 106
[16] Chen P, Li Y Q, Zhang Y C, Wu J Z, Ma J, Xiao L T, Jia S 2013 Chin. Phys. B 22 093301
[17] Ma J, Chen P, Liu W L, Feng G S, Li Y Q, Wu J Z, Xiao L T, Jia S T 2010 Acta Phys. Sin. 62 223301 (in Chinese) [马杰, 陈鹏, 刘文良, 冯国胜, 李玉清, 武寄洲, 肖连团, 贾锁堂 2010 物理学报 62 223301]
[18] Wu J Z, Ma J, Zhang Y C, Li Y Q, Wang L R, Zhao Y T, Chen G, Xiao L T, Jia S T 2011 Phys. Chem. Chem. Phys. 13 18921
[19] Bransden B H, Joachain C J 1983 Physics of Atoms and Molecules (Essex: Longman Publising Group)
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[1] Kajita M 2004 Phys. Rev. A 69 012709
[2] Jochim S, Bartenstein M, Altmeyer A, Hendl G, Chin C, Hecker Denschlag J, Grimm R 2003 Phys. Rev. Lett. 91 240402
[3] Wynar R, Freeland R S, Han D J, Ryu C, Heinzen D J 2000 Science 287 1016
[4] Pillet R, Drag C, Tolra B L 2001 Laser Phys. 11 480
[5] Tsai C, Freeland R, Vogels J, Boesten H 1997 Phys. Rev. Lett. 79 1245
[6] Wang J M 1999 Ph. D. Dissertation (Taiyuan: Shanxi University) (in Chinese) [王军民 1999 博士学位论文 (太原: 山西大学)]
[7] Jones K M, Tiesinga E, Lett P D, Julienne P S 2006 Rev. Mod. Phys. 78 483
[8] Jiang K J, Li K, Wang J, Zhan M S 2006 Acta Phys. Sin. 55 125 (in Chinese) [江开军, 李可, 王瑾, 詹明生 2006 物理学报 55 125]
[9] Zhang Y C, Wu J Z, Ma J, Zhao Y T, Wang L R, Xiao L T, Jia S T 2010 Acta Phys. Sin. 59 5418 (in Chinese) [张一驰, 武寄洲, 马杰, 赵延霆, 汪丽蓉, 肖连团, 贾锁堂 2010 物理学报 59 5418]
[10] Zhang W, Huang Y, Xie T, Wang G R, Cong S L 2010 Phys Rev. A 82 063411
[11] Fioretti A, Comparat D, Drag C, Amiot C, Dulieu O, Masnou-Seeuws F, Pillet P 1999 Eur. Phys. J. D 5 389
[12] Fioretti A, Comparat D, Drag C, Amiot C, Dulieu O, Masnou-Seeuws F, Pillet P 1998 Phys. Rev. Lett. 80 4402
[13] Comparat D, Drag C, Fioretti A, Dulieu O, Pillet P 1999 J. Mol. Spectrosc. 195 229
[14] Pichler M, Chen H, Stwalley W C 2004 J. Chem. Phys. 121 6779
[15] Ma J, Wang L R, Zhao Y T, Xiao L T, Jia S 2009 J. Mol. Spectrosc. 255 106
[16] Chen P, Li Y Q, Zhang Y C, Wu J Z, Ma J, Xiao L T, Jia S 2013 Chin. Phys. B 22 093301
[17] Ma J, Chen P, Liu W L, Feng G S, Li Y Q, Wu J Z, Xiao L T, Jia S T 2010 Acta Phys. Sin. 62 223301 (in Chinese) [马杰, 陈鹏, 刘文良, 冯国胜, 李玉清, 武寄洲, 肖连团, 贾锁堂 2010 物理学报 62 223301]
[18] Wu J Z, Ma J, Zhang Y C, Li Y Q, Wang L R, Zhao Y T, Chen G, Xiao L T, Jia S T 2011 Phys. Chem. Chem. Phys. 13 18921
[19] Bransden B H, Joachain C J 1983 Physics of Atoms and Molecules (Essex: Longman Publising Group)
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