共查询到20条相似文献,搜索用时 46 毫秒
1.
We present an ultra-high resolution spectroscopic study of the photoassociation of cesium atoms inside a magnetooptical trap using trap-loss detection with photoassociation laser slow scanning. The photoassociation spectra show vibrational levels of three molecular symmetries below the 6S 1/2 + 6P 3/2 dissociation limit. A dynamic model is derived to extract the photoassociation rate from the trap-loss spectrum. Many observed rotational levels are well resolved, which indicate d-wave and higher partial wave contributions to the photoassociation cross section. 相似文献
2.
Deiglmayr J Grochola A Repp M Mörtlbauer K Glück C Lange J Dulieu O Wester R Weidemüller M 《Physical review letters》2008,101(13):133004
Ultracold LiCs molecules in the absolute ground state X1Sigma+, v' = 0, J' = 0 are formed via a single photoassociation step starting from laser-cooled atoms. The selective production of v' = 0, J' = 2 molecules with a 50-fold higher rate is also demonstrated. The rotational and vibrational state of the ground state molecules is determined in a setup combining depletion spectroscopy with resonant-enhanced multiphoton ionization time-of-flight spectroscopy. Using the determined production rate of up to 5 x 10(3) molecules/s, we describe a simple scheme which can provide large samples of externally and internally cold dipolar molecules. 相似文献
3.
Ultracold molecules offer a broad variety of applications, ranging from metrology to quantum computing. However, forming "real" ultracold molecules, i.e., in deeply bound levels, is a very difficult proposition. Here, we show how photoassociation in the vicinity of a Feshbach resonance enhances molecular formation rates by several orders of magnitude. We illustrate this effect in heteronuclear systems, and find giant rate coefficients even in deeply bound levels. We also give a simple analytical expression for the photoassociation rate and discuss future applications of the Feshbach-optimized photoassociation technique. 相似文献
4.
The laser-intensity dependence of the photoassociation spectrum of the ultracold Cs_2(6S_(1/2) + 6P_(1/2))0_u~+ long-range molecular state 下载免费PDF全文
The high-resolution photoassociation spectrum of the ultracold cesium molecular 0_u~+ state below the 6S 1/2 + 6P 1/2 limit is presented in this paper. The saturation of the photoassociation scattering probability is observed from the dependence of the trap-loss probability on the photoassociation laser intensity. The corresponding resonant line width is also demonstrated to increase linearly with increasing photoassociation laser intensity. Our experimental data have good consistency with the theoretical saturation model of Bohn and Julienne Bohn J L and Julienne P S 1999 Phys. Rev. A 60 1]. 相似文献
5.
Drag C Laburthe Tolra B T'Jampens B Comparat D Allegrini M Crubellier A Pillet P 《Physical review letters》2000,85(7):1408-1411
In photoassociation spectroscopy, the line intensities of a given vibrational progression exhibit zero-signal modulation reflecting the node structure of the s-wave ground state wave function of two free colliding atoms. This leads to the determination of the scattering length. We performed photoassociation of cold Cs atoms polarized in the Zeeman sublevel f = 4, m(f) = 4. We analyzed the intensities of the lines associated with the Cs2 0(-)(g) state dissociating to the 6s(1/2)+6p(3/2) asymptote. This yields a value of the Cs triplet state scattering length, a(T) = -530a(0), while consistency requirements impose a value of the multipole ground state molecular coefficient, C6 = 6510 a.u. 相似文献
6.
Effect of external magnetic field on the shift of resonant frequency in photoassociation of ultracold Cs atoms 下载免费PDF全文
《中国物理 B》2019,(1)
We study the influence of external magnetic field on the shift of the resonant frequency in the photoassociation of ultracold Cs atoms, which are captured in a magnetically levitated optical crossed dipole trap. With the increase of the photoassociation laser intensity, the linear variation of the frequency shift is measured by recording the photoassociation spectra of the long-range 0_u~+ state of Cs molecule below the 6S_(1/2)+ 6P_(1/2) dissociation limit at different magnetic fields.The slope of the frequency shift to the intensity of the photoassociation laser exhibits a strong dependence on the external magnetic field. The experimental data is simulated with an analytic theory model, in which a single channel rectangular potential with the tunable well depth is introduced to acquire the influence of the magnetic field on the atomic behavior in the effective range where photoassociation occurs. 相似文献
7.
We have measured the intensity dependent rate and frequency shift of a photoassociation transition in a quantum degenerate gas of 7Li. The rate increases linearly with photoassociation laser intensity for low intensities, whereas saturation is observed at higher intensities. The measured rates and shifts agree reasonably well with theory within the estimated systematic uncertainties. Several theoretically predicted saturation mechanisms are discussed, but a theory in which saturation arises because of quantum mechanical unitarity agrees well with the data. 相似文献
8.
We simulate numerically the photodissociation of molecules into noncondensate atom pairs that accompanies photoassociation of an atomic Bose-Einstein condensate into a molecular condensate. Such rogue photodissociation sets a limit on the achievable rate of photoassociation. Given the atom density rho and mass m, the limit is approximately 6(planck)rho(2/3)/m. 相似文献
9.
Photoassociation inside an optical dipole trap: absolute rate coefficients and Franck–Condon factors
We present quantitative measurements of the photoassociation of cesium molecules inside a far-detuned optical dipole trap. A model of the trap-depletion dynamics is derived which allows us to extract absolute photoassociation rate coefficients for the initial single-photon photoassociation step from measured trap-loss spectra. The sensitivity of this approach is demonstrated by measuring the Franck–Condon modulation of the weak photoassociation transitions into the low-vibrational levels of the outer well of the Og- state that correlates to the 6s+6p3/2 asymptote. The measurements are compared to theoretical predictions. In a magneto-optical trap, these transitions have previously only been observed indirectly through ionization of ground-state molecules. PACS 34.50.Rk; 33.70.Ca; 32.80.Pj 相似文献
10.
通过激光冷却技术在磁光阱中俘获原子数约107,温度约200 μK,直径约400 μm的超冷铯原子,利用超冷铯原子光缔合方法制备了激发态的超冷铯分子。实验研究了光缔合光不同扫描速率对铯分子振转光谱分辨率的影响,发现光缔合光扫描速率较慢时,铯分子振转光谱分辨率较高。通过高灵敏的雪崩光电探测器探测冷原子荧光,获得了超冷铯分子第一激发态6S1/2+6P3/2离解限0-g长程态高分辨振转光谱。为了实现受控拉曼光缔合制备超冷基态分子,光缔合激光频率需要锁定在原子-分子共振跃迁线,对超冷原子光缔合光谱进行了超低频波长调制,通过改变调制幅度和调制频率获得最优化的一阶微分信号,将该信号反馈回激光器,实现闭合环路稳频,满足了受控拉曼光缔合制备振转能级可控的基态分子的实验要求,该工作对研究受限空间中的超冷原子分子具有很重要的意义。 相似文献
11.
12.
Highly sensitive photoassociation spectroscopy of ultracold ~(23)Na~(133)Cs molecular long-range states below the 3S_(1/2)+6P_(3/2)limit 下载免费PDF全文
We present high resolution photoassociation spectroscopy of ultracold~(23)Na~(133)Cs molecules in a long-range c~3Σ~+state below the(3 S_(1/2)+ 6 P_(3/2)) asymptote. We perform photoassociation spectroscopy in a dual-species magneto-optical trap(MOT) and detect the photoassociation resonances using trap-loss spectroscopy. By fitting the experimental data with the semi-classical Le Roy–Bernstein formula, we deduce the long-range molecular coefficient C6 and derive the empirical potential energy curve in the long-range region. 相似文献
13.
Wang LiRong Ma Jie Ji WeiBang Wang GuiPing Xiao LianTuan Jia SuoTang 《中国科学G辑(英文版)》2008,51(2):147-156
In this paper, an ultra-high resolution photoassociation spectroscopy study on photoassociation of cesium atoms is reported.
The cold cesium gas in the magneto-optical trap is illuminated by a photoassociation laser with red-tuning as large as 40
cm−1 below the 6S
1/2 + 6P
3/2 dissociation limit, and the photoassociation to the excited state ultracold molecule is detected. High signal-to-noise ratio
is obtained by using the lock-in detection of the fluorescence from the modulated cold Cs atoms. The 0
g
−
, 1g and 0
u
+
long-range states which correspond to 6S
1/2 + 6P
3/2 dissociation limit are present in the photoassociation spectrum. The effective coefficients of leading long-range interactions
and the corresponding vibrational quantum number are obtained using LeRoy-Bernstein Law. It is found that photoassociation
process creates rotating molecules and the high J value is a hint that higher partial waves participate in the PA process in the presence of trapping laser.
Supported by 973 Program of China (Grant. No. 2006CB921603), the National Natural Science Foundation of China (Grant Nos.
10574084, 60678003, and 60778008), the Special Foundation for State Major Basic Research Program of China (Grant No. 2005CCA06300),
and the Youth Science Foundation of Shanxi Province of China (Grant No. 20041013) 相似文献
14.
An ultrahigh resolution photoassociation spectrum of caesium atoms in a magneto-optical trap is presented. Hyperfine structure of the excited state molecule is obtained by using the lock-in method based on modulated cold atoms in this spectrum. Amplitude of resonant lines related to the rotational levels increases with photoassociation laser intensity, and saturation effect of photoassociation of cold atoms is observed in our experiment. The saturation intensity of photoassociation is deduced by fitting the experimental data to asaturation model based on scattering theory. Differences among saturation intensities of different rotational progressions in the υ=55 vibrational state of the caesium molecular long-range 0g- state have been found. 相似文献
15.
We discuss the dynamics of an atomic Bose-Einstein condensate when pairs of atoms are converted into molecules by single-color photoassociation. Three main regimes are found, and it is shown that they can be understood on the basis of time-dependent two-body theory. In particular, the so-called rogue dissociation regime [Phys. Rev. Lett. 88, 090403 (2002)10.1103/PhysRevLett.88.090403], which has a density-dependent limit on the photoassociation rate, is identified with a transient regime of the two-atom dynamics exhibiting universal properties. Finally, we illustrate how these regimes could be explored by photoassociating condensates of alkaline-earth atoms. 相似文献
16.
The formation of ultracold metastable RbCs molecules is observed in a double species magneto-optical trap through photoassociation below the 85Rb(5S1/2) + 133Cs(6P3/2) dissociation limit followed by spontaneous emission. The molecules are detected by resonance enhanced two-photon ionization. Using accurate quantum chemistry calculations of the potential energy curves and transition dipole moment, we interpret the observed photoassociation process as occurring at short internuclear distance, in contrast with most previous cold atom photoassociation studies. The vibrational levels excited by photoassociation belong to the 5th 0+ or the 4th 0? electronic states correlated to the Rb(5P1/2, 3/2) + Cs(6S1/2) dissociation limit. The computed vibrational distribution of the produced molecules shows that they are stabilized in deeply bound vibrational states of the lowest triplet state. We also predict that a noticeable fraction of molecules is produced in the lowest level of the electronic ground state. 相似文献
17.
We report photoassociation spectroscopy of 174Yb for the 1S(0)-1P1 transition at 1 microK, where only the s-wave scattering state contributes to the spectra. The wave function of the s-wave scattering state is obtained from the photoassociation efficiency, and we determine that the C6 potential coefficient is 2300+/-250 a.u. and the s-wave scattering length is 5.53+/-0.11 nm. Based on these parameters, we discuss the scattering properties of s- and d-wave states. 相似文献
18.
Takasu Y Komori K Honda K Kumakura M Yabuzaki T Takahashi Y 《Physical review letters》2004,93(12):123202
We report the photoassociation spectroscopy of laser-cooled ytterbium atoms in an optical trap. We observed more than 90 photoassociation resonances of vibrational levels in the (1)Sigma(+)(u) state, including 80 consecutive series, up to 490 GHz detuning with respect to the atomic resonance. From the resonance frequencies we derived the atomic radiative lifetime of the (6s6p) 1P1 state to be 5.464+/-0.005 ns, which is about 2 orders of magnitude improvement over previous results. We also observed line broadening of resonances, which is ascribed to the predissociation to the triplet states, and estimated the transition probability to be 0.2. Furthermore, we observed the decrease of the photoassociation signal intensity, from which the scattering length is estimated to be equal to or less than 3 nm. 相似文献
19.
Moal S Portier M Kim J Dugué J Rapol UD Leduc M Cohen-Tannoudji C 《Physical review letters》2006,96(2):023203
We present a new measurement of the s-wave scattering length a of spin-polarized helium atoms in the 2(3)S1 metastable state. Using two-photon photoassociation spectroscopy and dark resonances, we measure the energy E(nu)=14= -91.35+/- 0.06 MHz of the least-bound state nu = 14 in the interaction potential of the two atoms. We deduce a value of a=7.512+/-0.005 nm, which is at least 100 times more precise than the best previous determinations and is in disagreement with some of them. This experiment also demonstrates the possibility to create exotic molecules binding two metastable atoms with a lifetime of the order of 1 micros. 相似文献