Ionization spectroscopy in cold rubidium atoms (original) (raw)
Related papers
Photoionization Cross-Section Measurements of the 5P3/2 Excited State of Laser-Cooled Rubidium
2010
Photoionization cross-section measurements are relevant for fundamental tests of the atomic theory, as well as state-selective detection of trapped atomic and molecular species and plasma research, including ultracold plasma formation. We have extended the current photoionization cross-section measurements of the 5P3/2 exited state of rubidium by including three additional wavelengths close to the ionization threshold of 479.1 nm. The measurements were performed in a rubidium magneto-optical trap using several lines from a mixed argon-krypton ion laser ranging from 457.9 nm to 476.5 nm. The photoionization rate for each wavelength was determined from the loss rate of atoms in the trap during exposure to the ionizing laser radiation. Our results are in good agreement with other experimental results and allow for comparison with theoretical predictions of the photoionization cross section versus the ionizing photon energy.
Detection by two-photon ionization and magnetic trapping of cold Rb2 triplet state molecules
The European Physical Journal D, 2006
We present detailed experimental spectra and accurate theoretical interpretation of resonanceenhanced two-photon ionization of ultracold rubidium molecules in the 14000-17000 cm −1 transition energy range. The dimers are formed in a magneto-optical trap by photoassociation followed by radiative decay into the a 3 Σ + u lowest triplet state. The theoretical treatment of the process, which reproduces the main features of the spectra, takes into account the photoassociation and decay steps as well as the resonant ionization through the manifold of intermediate gerade states correlated to the 5S + 4D limit. In particular, the energy of the v = 1 level of the (2) 3 Σ + g potential well has been determined for the first time. In addition, a tight constraint has been put on the position of the a 3 Σ + u repulsive wall. Finally, magnetic trapping of rubidium molecules in the a 3 Σ + u state is demonstrated.
Investigation of cold rubidium Rydberg atoms in a magneto-optical trap
Journal of Experimental and Theoretical Physics, 2009
We present our results on the experiments with cold Rb Rydberg atoms in a magneto-optical trap (MOT). Characteristic features of our experiment were the excitation of Rydberg atoms in a small volume within the cold atom cloud and sorting of the measured signals and spectra over the number of registered Rydberg atoms. We have measured the effective lifetime of the Rydberg state 37P, as well as its polarizability in a weak electric field. The results are in good agreement with the theoretical calculations. We have shown that localization of the small excitation volume around the zero-magnetic-field point makes possible to increase the spectral resolution and to obtain narrow microwave resonances in Rydberg atoms without switching off the MOT quadrupole magnetic field. We have measured the dependence of the amplitude of the dipole-dipole interaction resonances on the number of Rydberg atoms, which has a linear character and agrees with the theory for weak dipole-dipole interaction.
An optical trap for cold rubidium molecules
Optics Communications, 2004
We report on optical trapping ultracold rubidium molecules. The molecules are produced in the ground triplet state through photoassociation and radiative decay from laser-cooled atoms and are confined in the focus of a CO 2 laser beam. The molecules are observed by photoionization and ion detection.
Absorption spectroscopy of trapped rubidium atoms
Canadian Journal of Physics, 2004
We determine the absolute density of a sample of laser-cooled atoms in a two-level system by recording the absorption spectrum of the 85Rb 5S1/2 (F = 3, mf = 3) → 5P3/2 (F′ = 4, m′f = 4) transition. Trapped atoms were prepared in the (F = 3, mf = 3) ground state through optical-pumping techniques. We compare our results with an independent measure of the density that relies on a direct measurement of the number of atoms and size of the atomic sample. We also study the contributions of power broadening, laser line width, and Doppler broadening to the measured absorption spectrum. Our studies suggest that the natural line width (~6 MHz) can be measured to a precision of less than ~50 kHz if the laser line width is measured in real-time with a high-finesse Fabry–Perot cavity. PACS Nos.: 32.70.Cs, 32.70.Jz, 32.80.Pj, 42.62.Fi, 32.70.–n, 32.30.–r
Coherent control of multiphoton-ionization passage of excited-state rubidium atoms
Physical Review A, 2012
We have investigated multiphoton-ionization passages of rubidium atoms initiated from the excited 5P 3/2 energy state. For this we used coherent control schemes based on femtosecond laser pulse shaping applied to cold atoms spatially isolated in a magneto-optical trap. With programed laser pulses of spectral π-phase step, of which location was varied within the laser spectrum, the sequential two-photon-ionization passage along the 5P 3/2-5D continuum was probed in terms of trap-loss spectroscopy. The coherent control two-photon-ionization method unveiled not only the resonantly enhanced two-photon ionization but also the asymmetric nature of the ionization profile structure given as a function of the spectral phase step location. Experimental results show good agreement with the second-order perturbation calculation of the constituent possible ionization passages.
Physical Review A, 2013
We measure the collision rate coefficient between laser cooled Rubidium (Rb) atoms in a magnetooptical trap (MOT) and optically dark Rb + ions in an overlapping Paul trap. In such a mixture, the ions are created from the MOT atoms and allowed to accumulate in the ion trap, which results in a significant reduction in the number of steady state MOT atoms. A theoretical rate equation model is developed to describe the evolution of the MOT atom number, due to ionization and ion-atom collision, and derive an expression for the ion-atom collision rate coefficient. The loss of MOT atoms is studied systematically, by sequentially switching on the various mechanisms in the experiment. Combining the measurements with the model allows the direct determination of the ion-atom collision rate coefficient. Finally the scope of the experimental technique developed here is discussed.
Journal of Experimental and Theoretical Physics, 2013
The spectra of the three photon laser excitation 5S 1/2 5P 3/2 6S 1/2 nP of cold Rb Rydberg atoms in an operating magneto optical trap based on continuous single frequency lasers at each stage are studied. These spectra contain two partly overlapping peaks of different amplitudes, which corre spond to coherent three photon excitation and incoherent three step excitation due to the presence of two different ways of excitation through the dressed states of intermediate levels. A four level theoretical model based on optical Bloch equations is developed to analyze these spectra. Good agreement between the exper imental and calculated data is achieved by introducing additional decay of optical coherence induced by a finite laser line width and other broadening sources (stray electromagnetic fields, residual Doppler broaden ing, interatomic interactions) into the model.
Journal of Applied Research and Technology, 2015
The design and construction of an experimental system for studying two photon spectroscopy processes in atomic rubidium is presented. It is designed to measure absorption and polarization rotation induced by any of the two laser beams and also the visible fluorescence that results from decay of the excited states. Two home-built diode lasers are used to produce the optical fields that later interact with room temperature rubidium atoms. Using counterpropagating beams allows velocity selection of the groups of atoms that interact with both laser beams. The system was tested in the 5 S → 5 P 3/2 → 5 D j ladder energy level configuration of atomic rubidium. Blue fluorescence (420 nm) that results from decay of the intermediate 6P j states is filtered and then measured with a photomultiplier tube. Absorption and fluorescence spectra provide mutually complementary information about the interaction between the rubidium atoms and the two optical fields.
The European Physical …, 2001
We report the detailed analysis of translationally cold rubidium molecule formation through photoassociation. Cold molecules are formed after spontaneous decay of photoexcited molecules from a laser cooled atomic sample, and are detected by selective mass spectroscopy after two-photon ionization into Rb + 2 ions. A spectroscopic study of the 0 − g (5S + 5P 3/2 ) pure long-range state of 87 Rb2 is performed by detecting the ion yield as a function of the photoassociation laser frequency; the spectral data are theoretically analyzed within the semiclassical RKR approach. Molecular ionization is resonantly enhanced through either the 2 3 Πg or the 2 3 Σ + g intermediate molecular states. Some vibrational levels of the latter electronic state are observed and assigned here for the first time. Finally, cold molecules formation rates are calculated and compared to the experimentally measured ones, and the vibrational distribution of the formed molecules in the a 3 Σ + u ground triplet state is discussed.