Testing the distance-dependence of the van der Waals interaction between an atom and a surface through spectroscopy in a vapor nanocell (original) (raw)
Related papers
Exploring the van der Waals atom-surface attraction in the nanometric range
Europhysics Letters (EPL), 2007
Optical tests of quantum theory 34.50.Dy Interactions of atoms and molecules with surfaces; photon and electron emission; neutralization of ions 32.70.Jz Line shapes, widths, and shifts The van der Waals atom-surface attraction, scaling as C 3 z-3 for z the atom-surface distance, is expected to be valid in the distance range 1-1000 nm, covering 8-10 orders of magnitudes in the interaction energy. A Cs vapour nanocell allows us to analyze the spectroscopic modifications induced by the atom-surface attraction on the 6P 3/2 →6D 5/2 transition. The measured C 3 value is found to be independent of the thickness in the explored range 40-130 nm, and is in agreement with an elementary theoretical prediction. We also discuss the specific interest of exploring short distances and large interaction energy.
Probing an atomic gas confined in a nanocell
Journal of Physics: Conference Series, 2005
Since the recent realization of extremely thin vapour cells (local thickness: 20-1000 nm), we investigate the optical properties of these 1-D confined vapours. Aside from their interest for Doppler-free spectroscopy, nanocells offer a new tool to evaluate collisional shift and broadening, yielding an access to the open problem of collisions under confinement. It also allows probing of the atom-surface interaction in a range of unusual short distances. The experimental exploration of the distance dependence, normally evolving according to the z-3 van der Waals (vW) dependence (z : the atom-surface distance), is worth doing because it could be affected by imperfections of the real surface, such as roughness, adsorbed impurities or charges. A detailed lineshape analysis is now under progress, with tight constraints imposed to the fitting by the twin information brought by simultaneous reflection and transmission spectra. Another issue is a possible resonant enhancement, susceptible to induce a repulsive vW, due to the coupling between atom excitation and a surface mode.
Atom-surface van der Waals repulsion
We explore experimentally a situation when the van der Waals long-range atom-surface interaction is turned into epulsion, as due to a resonant coupling between a virtual emission of the excited atom, and a virtual absorption of the dielectric surface in a polariton mode.
EPL (Europhysics Letters), 2012
van der Waals-Zeeman transitions between magnetic states of metastable rare gas atoms Ar*, Kr* and Xe* ( 3 P 2 ) induced by a solid surface in the presence of a magnetic field, are investigated theoretically and experimentally. By use of a Zeeman slower, metastable argon atoms with various velocities ranging from 170 to 560 m/s allow us to investigate the small impact-parameter range (3-7 nm) within which these transitions occur, as well as the effect of atom polarisation on the sharing out of the M states.
Anisotropic atom-surface interactions in the Casimir-Polder regime
Physical Review A, 2014
The distance-dependence of the anisotropic atom-wall interaction is studied. The central result is the 1/z 6 quadrupolar anisotropy decay in the retarded Casimir-Polder regime. Analysis of the transition region between non-retarded van der Waals regime (in 1/z 3 ) and Casimir-Polder regime shows that the anisotropy cross-over occurs at very short distances from the surface, on the order of 0.03λ, where λ is the atom characteristic wavelength. Possible experimental verifications of this distance dependence are discussed. PACS numbers: 34.35.+a, 03.75.Be, 12.20.Fv The force between neutral polarisable systems is a ubiquitous phenomenon in nature, with many applications in physics, chemistry, biology. . . A paramount example is the long-range interaction potential between neutral microscopic quantum systems, like atomic systems, and a solid surface. For plane surfaces this interaction is usually governed by a power-law attractive potential . For atom-surfaces distances z smaller than the wavelengths of the optical transitions involved in the atomic polarisability, the interaction is of the dipoleinduced dipole type, and governed by the well-known non-retarded van der Waals potential in −C 3 /z 3 , which reflects the correlations of dipole fluctuations [1]. At larger distances, retardation effects get important, and asymptotically lead to a −C 4 /z 4 potential, as demonstrated in the pioneering work of Casimir and Polder [2].
Measuring the van der Waals forces between a Rydberg atom and a metallic surface
Physical review. A, 1988
We have observed the deflection of Rydberg atoms towards a metallic surface by the van der %'aals force. Cs and Na atoms in states of principal quantum number n were sent between two parallel gold-coated mirrors, spaced by a gap m (2.1 pm & au & 8.5 pm). %e measured the value n at which the transmission cuts off' and from the variation of n versus u, we obtained a measure of the atom-surface interaction. For 12' n g30 this interaction is 3-4 orders of magnitude larger than for ground-state atoms"and it obeys the scaling laws of the Lennard-Jones model. The van der Waals interaction between a metallic surface and an atom is an Important process in atomic physics. If the metal behaves as a perfect conductor at characteristic atomic frequencies, the interaction can be viewed, after Lennard-Jones, ' as resulting from the coupling of the atomic dipole with its electrostatic images in the surface. This coupling gives rise to energy-level shifts proportional to z 3 (where z is the atom-surface dis-tance}, and the derivative of these shifts with respect to the distance corresponds to the dipole-image van der Waals force Fvw-z that puBs the atom towards the metal. This assumes that z is small compared with any characteristic atomic-transition wavelength so that retardation is negligible.
van der Waals energy of an atom in the proximity of thin metal films
Physical Review A, 2000
The van der Waals energy of a ground-state atom ͑or molecule͒ placed between two metal films is calculated at finite temperature. The attraction between thin metal films and a polarizable object can have half-integer separation dependence. This is in contrast to the usual integer separation dependence, shown for instance in the attraction between an atom and a solid surface. We examine how film thickness, retardation, and temperature influence the interaction. To illustrate the effect of finite thickness of the metal film we calculated the van der Waals energy of ground-state hydrogen and helium atoms, and hydrogen molecules, between thin silver films. We finally, briefly, discuss the possibility to measure this effect.
Interferometric approaches to atom-surface van der Waals interactions in atomic mirrors
Physical Review A, 1999
We analyze the possibilities of approaching atom-surface interactions through their contribution to the atomic matter de Broglie wave phase, in an interferometer based on an evanescent light atomic mirror. The surface interactions produce an additional phase shift that is evaluated to a few times for a neon atom in a metastable state. We propose and investigate an experimental procedure that uses the principles of polarization ͑for instance, Stern-Gerlach͒ interferometers in order to monitor these long-range interactions ͑van der Waals, Casimir-Polder, etc.͒ between a ground-state or metastable-state atom and either a metallic or a dielectric surface. Our approach gives access to the differential phase shift between Zeeman sublevels, and should then be sensitive to an eventual anisotropy of the atom-surface interaction.