Preliminary experimental results are reported for the deflection of Na atoms in an atomic beam by a transverse standing-wave laser field whose frequency is tuned between the two ground-state hyperfine components of the Z^ line. In contrast to the two experiments done previously, a splitting of the beam into two symmetric peaks whose separation increases with the electric-field is seen here. In addition, the data show evidence for atomic diffraction: a tendency for scattered atoms to acquire momentum in multiples of 2h~k.PACS numbers: 32.80. Kf, 32.90.+a We present preliminary measurements of the momentum transferred to a beam of Na atoms by a perpendicularly oriented, near-resonant, standing-wave radiation field. Our measurements were made in an apparatus of high angular resolution and short atom-field interaction time (~1 radiative lifetime). In contrast to two previous experiments on the deflection of atoms by standing-wave fields, 1 ' 2 our results show that the atomic beam is split into two symmetrical peaks whose separation is proportional to the electric field of the radiation. This result is in qualitative agreement with the theoretical predictions valid for our off-resonant radiation. 3 * 4 In addition, we observed a clustering in the momentum distribution of scattered atoms into multiples of 2Kk.We outline here the basic arguments which lead to the two-peaked distribution. Because of the short interaction time, we neglect spontaneous decay in the following discussion.A recent and widely applied theoretical treatment of an atom in an intense optical-frequency field is the dressed-atom approach, 5 which is a solution of the atom plus field considered as a single system. For a two-state atom with a dipole matrix element, jit, the eigenvalues are E = ±h(w R 2 + A 2 /4) l/2 , where a^= /x e/fi (the Rabi frequency), € is the field amplitude, and A is the laser detuning from resonance.The eigenvalue, E, is the potential energy of interaction between the field and the atom, and hence the atom experiences a net force along or against the field gradient. This pushes an atom into or out of regions of high field (the force on an atom or molecule due to an interaction of the induced dipole moment with a field gradient has been observed in several experiments; see Bloom, Enga, and Lew, 6 Hill and Gallagher, 7 and Bjorkholm et a/. 8 ). For A =0, an entering atom is in an equal superposition of "weak-" and "strong-field seeking" states. For off-resonant radiation, the magnitude of A and the speed of entry of the atom into the field determine the state population.With use of the gradient force, and the easily satisfied condition that the atom moves along the field gradient by much less than an optical wavelength in its traversal of the field, the momentum distribution for atoms scattered by a standingwave field, e(x) =2e 0 cos£x, may be calculated. For A = 0, a classical calculation yieldswhere p m = fiku R T, and / is the total beam flux. This predicts a splitting of the beam: a pattern which is small in the center, ...
We present a thorough spectroscopic study of the van der Waals molecule NaNe. Our molecular beam apparatus, laser scanning system, and frequency reference technique are described in detail. Methods of rotational analysis are discussed. Descriptions of the observed vibration–rotation bands in the A 2Πr–X 2Σ+ and B 2Σ+–X 2Σ+ manifolds are presented. Perturbations in the observed spectra are discussed. Long range analysis techniques are used to determine the vibrational quantum numbering from observed isotopic shifts and to determine excited and ground state potential parameters. We find DeA=145±05 cm−1 at ReA=5.1(1)a0, DeX=8.1(9) cm−1 at ReX=10.0(1)a0, and DeB?3.0(5) cm−1 at ReB?14.4(3)a0.
Knowledge of the Hg(3P1) spatial distribution in Hg rare gas low pressure discharges is important for understanding radiation transport, and aids in the formulation of discharge models for fluorescent lamps. We report on a novel single laser, two intersecting beams technique, which, for the first time, yields pinpoint information on the radial density profile of excited state mercury in the discharge positive column. Advantages over conventional single beam absorption are discussed, and preliminary data for a discharge containing one isotope (198Hg) of mercury and 2.5 Torr argon are presented.
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