Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Bulletin of the American Physical Society

Experimental investigations of relaxation of spin polarized atoms on coated surfaces

Natarajan D. Bhaskar

Published May 1, 1993• 0 citations
OpenAlex

Abstract

The interaction of spin polarized cesium atoms on coated surfaces is examined. Coated surfaces find extensive applications in atomic devices-hydrogen masers and advanced rubidium frequency standards utilize wall coatings to obtain very narrow hyperfine resonances. A Cs atomic beam is hyperfine or spin polarized by optical pumping techniques using a single mode AlGaAs diode laser. The ground state distribution is probed before and after scattering from coated surfaces using laser induced fluorescence spectroscopy. The coatings under investigations are paraffin and organosilanes and these are known to be very weakly relaxing surfaces for polarized alkali atoms. The spin relaxation properties of paraffin and organosilane coatings have been studied in glass cell-vapor environment. In our experiments using polarized atomic beams, our goal is to examine in detail the hyperfine and spin relaxation properties of these coatings in a carefully controlled environment which is not possible in the gas cell environment. We measure the spin relaxation probability per wall collision as a function of temperature of the surface. Results of our studies will be presented.

Related papers

Relaxation of atomic polarization in paraffin-coated cesium vapor cells

M. T. Graf, Derek F. Jackson Kimball, Simon Rochester +6 more

The relaxation of atomic polarization in buffer-gas-free, paraffin-coated cesium vapor cells is studied using a variation on Franzen's technique of ``relaxation in the dark'' [Franzen, Phys. Rev. 115 850 (1959)]. In the present experiment, narrow-band, circularly polarized pump light, resonant with the Cs D2 transition, orients atoms along a longitudinal magnetic field, and time-dependent optical rotation of linearly polarized probe light is measured to determine the relaxation rates of the atomic orientation of a particular hyperfine level. The change in relaxation rates during light-induced atomic desorption (LIAD) is studied. No significant change in the spin relaxation rate during LIAD is found beyond that expected from the faster rate of spin-exchange collisions due to the increase in Cs density.

arXiv:physics/0503202•Physical Review A•Aug 1, 2005•140 citations

Investigation of antirelaxation coatings for alkali-metal vapor cells using surface science techniques

Scott J. Seltzer, David J. Michalak, Marcus H. Donaldson +17 more

Many technologies based on cells containing alkali-metal atomic vapor benefit from the use of antirelaxation surface coatings in order to preserve atomic spin polarization. In particular, paraffin has been used for this purpose for several decades and has been demonstrated to allow an atom to experience up to 10 000 collisions with the walls of its container without depolarizing, but the details of its operation remain poorly understood. We apply modern surface and bulk techniques to the study of paraffin coatings in order to characterize the properties that enable the effective preservation of alkali spin polarization. These methods include Fourier transform infrared spectroscopy, differential scanning calorimetry, atomic force microscopy, near-edge x-ray absorption fine structure spectroscopy, and x-ray photoelectron spectroscopy. We also compare the light-induced atomic desorption yields of several different paraffin materials. Experimental results include the determination that crystallinity of the coating material is unnecessary, and the detection of C[Double Bond]C double bonds present within a particular class of effective paraffin coatings. Further study should lead to the development of more robust paraffin antirelaxation coatings, as well as the design and synthesis of new classes of coating materials.

arXiv:1002.4417•The Journal of Chemical Physics•Oct 11, 2010•63 citations

Interaction of spin-polarized atoms with a surface studied by optical-reflection spectroscopy

S. Grafström, Dieter Suter

We present an experiment for the investigation of the interaction of spin-polarized Na atoms with a dielectric surface. A laser beam, which is resonant with an atomic transition, probes the spin polarization near the surface. It is reflected at the surface and the change of its polarization is measured. Our analysis takes into account that the spin polarization is reduced near the surface because of surface-induced spin relaxation. The theory shows that strong wall relaxation leads to a clear modification of the shape and strength of the optical line. The dependence of the line shape on the angle of incidence immediately below the critical angle of total internal reflection provides a sensitive tool for the quantitative determination of the depolarization probability \ensuremath{\varepsilon} per wall collision. Measurements performed at a Pyrex glass surface provide a clear experimental confirmation of the theory and yield a value of \ensuremath{\varepsilon}\ensuremath{\approxeq}0.5. The case of weak wall relaxation is exemplified by experimental results from a silicone-coated glass surface, which are equally well reproduced by the theory. The method offers the prospect of using surface-induced spin relaxation for the study of surface properties and atom-surface interactions for various surfaces. \textcopyright{} 1996 The American Physical Society.

Physical Review A•Sep 1, 1996•17 citations

Relaxation of Cs atomic polarization at surface coatings characterized by X-ray photoelectron spectroscopy

Kotaro Kushida, Toshihiro Niwano, Takemasa Moriya +4 more

Abstract Paraffin coatings on glass slides were investigated through both X-ray photoelectron spectroscopy (XPS) and spin relaxation measurement for cesium (Cs) vapor. The components of the glass substrate, such as silicon and oxygen, existed in the XPS spectra of the coated slides, indicating the imperfection of the prepared paraffin coatings. The substrate was not observed after the annealing of the coatings in Cs vapor, which is known as a “ripening” process for spin relaxation measurement. We found a general trend that effective anti-spin relaxation performance requires high paraffin and low Cs coverage on the surface. We also examined a type of diamond-like carbon film, anticipating the effect of anti-spin relaxation; our attempts have failed to date.

arXiv:1410.8321•Japanese Journal of Applied Physics•May 1, 2015•3 citations

The study of wall interactions of spin polarized rubidium atoms using the frequency shift in the electron paramagnetic resonance of the rubidium atoms

Emily Ulanski

I studied the effect of wall collisions on the electron paramagnetic resonance (EPR) of gas phase alkali metal atoms (87Rb). Two types of walls were studied: antirelaxation-coated walls and RbH-coated walls. I measured the dwell times of spin polarized Rb atoms on the two most common antirelaxation coatings, octadecyltrichlorosilane (OTS)- and paraffin. I found that at a cell temperature of 72 C the dwell times for OTS- and paraffin-coated walls are 0.9 ± 0.1 μs and 1.8 ± 0.2 μs, respectively. The implication of these dwell times, which are much longer than what was previously reported in the literature, is discussed in connection with the relaxing property of these coatings. In cells coated with RbH salt I made the first observation of the EPR frequency shift of the gas phase 87Rb atoms. Due to collisions with the RbH salt, which was nuclear spin polarized by spin exchange with optically pumped Rb vapor. The measured EPR frequency shifts are of the order of several hundred Hz in a millimeter-sized cell. By measuring the dependence of the EPR frequency shifts on cell length and by comparing the EPR frequency shifts in RbH-coated cells with those in OTS-coated cells, I provided convincing evidence that the observed EPR frequency shifts are due to collisions with RbH-coated walls, and not due to gas phase processes. The EPR frequency shift is due to the Fermi contact interaction between the s-electron of the adsorbed 87Rb atom and the polarized nucleus on the salt surface. The measured EPR frequency shifts allowed me to calculate the ensemble-averaged phase shift experienced by the Rb atom while adsorbed on the walls. Under our experimental condition this is about 70 mrad. My experiment opens up the possibility of studying surface NMR using gas phase EPR. The phase shift is proportional to the surface nuclear polarization, thus provides an interesting method for measuring the surface nuclear polarization using gas phase EPR. My observation will alert the high precision miniature atomic magnetometry community that collisions with cell walls may cause a systematic error and line broadening in the magnetic resonance frequency.

•Jan 1, 2014•0 citations

Light-induced desorption of alkali-metal atoms from paraffin coating

Evgeny B. Alexandrov, M. V. Balabas, Dmitry Budker +4 more

Observation of nonthermal, light-induced desorption of Cs and Rb atoms from paraffin coating is reported. Buffer-gas-free paraffin-coated cells containing Cs and Rb were exposed to laser light of various intensities and frequencies, and the change of the vapor densities as a function of time was investigated. Because atomic polarization relaxes very slowly in paraffin-coated cells (spin-relaxation times can be $\ensuremath{\gtrsim}1\mathrm{s}),$ they are applied in a variety of precision measurements (e.g., magnetometry, discrete symmetry tests, etc.). Light-induced desorption may be useful in such measurements as a method to control atomic density without changing the temperature of the cell.

Physical Review A•Oct 23, 2002•154 citations
The interaction of spin polarized cesium atoms on coated surfaces is examined. Coated surfaces find extensive applications in atomic devices-hydrogen masers and advanced rubidium frequency standards utilize wall coatings to obtain very narrow hyperfine resonances. A Cs atomic beam is hyperfine or spin polarized by optical pumping techniques using a single mode AlGaAs diode laser. The ground state distribution is probed before and after scattering from coated surfaces using laser induced fluorescence spectroscopy. The coatings under investigations are paraffin and organosilanes and these are known to be very weakly relaxing surfaces for polarized alkali atoms. The spin relaxation properties of paraffin and organosilane coatings have been studied in glass cell-vapor environment. In our experiments using polarized atomic beams, our goal is to examine in detail the hyperfine and spin relaxation properties of these coatings in a carefully controlled environment which is not possible in the gas cell environment. We measure the spin relaxation probability per wall collision as a function of temperature of the surface. Results of our studies will be presented.
The relaxation of atomic polarization in buffer-gas-free, paraffin-coated cesium vapor cells is studied using a variation on Franzen's technique of ``relaxation in the dark'' [Franzen, Phys. Rev. 115 850 (1959)]. In the present experiment, narrow-band, circularly polarized pump light, resonant with the Cs D2 transition, orients atoms along a longitudinal magnetic field, and time-dependent optical rotation of linearly polarized probe light is measured to determine the relaxation rates of the atomic orientation of a particular hyperfine level. The change in relaxation rates during light-induced atomic desorption (LIAD) is studied. No significant change in the spin relaxation rate during LIAD is found beyond that expected from the faster rate of spin-exchange collisions due to the increase in Cs density.
Many technologies based on cells containing alkali-metal atomic vapor benefit from the use of antirelaxation surface coatings in order to preserve atomic spin polarization. In particular, paraffin has been used for this purpose for several decades and has been demonstrated to allow an atom to experience up to 10 000 collisions with the walls of its container without depolarizing, but the details of its operation remain poorly understood. We apply modern surface and bulk techniques to the study of paraffin coatings in order to characterize the properties that enable the effective preservation of alkali spin polarization. These methods include Fourier transform infrared spectroscopy, differential scanning calorimetry, atomic force microscopy, near-edge x-ray absorption fine structure spectroscopy, and x-ray photoelectron spectroscopy. We also compare the light-induced atomic desorption yields of several different paraffin materials. Experimental results include the determination that crystallinity of the coating material is unnecessary, and the detection of C[Double Bond]C double bonds present within a particular class of effective paraffin coatings. Further study should lead to the development of more robust paraffin antirelaxation coatings, as well as the design and synthesis of new classes of coating materials.
We present an experiment for the investigation of the interaction of spin-polarized Na atoms with a dielectric surface. A laser beam, which is resonant with an atomic transition, probes the spin polarization near the surface. It is reflected at the surface and the change of its polarization is measured. Our analysis takes into account that the spin polarization is reduced near the surface because of surface-induced spin relaxation. The theory shows that strong wall relaxation leads to a clear modification of the shape and strength of the optical line. The dependence of the line shape on the angle of incidence immediately below the critical angle of total internal reflection provides a sensitive tool for the quantitative determination of the depolarization probability \ensuremath{\varepsilon} per wall collision. Measurements performed at a Pyrex glass surface provide a clear experimental confirmation of the theory and yield a value of \ensuremath{\varepsilon}\ensuremath{\approxeq}0.5. The case of weak wall relaxation is exemplified by experimental results from a silicone-coated glass surface, which are equally well reproduced by the theory. The method offers the prospect of using surface-induced spin relaxation for the study of surface properties and atom-surface interactions for various surfaces. \textcopyright{} 1996 The American Physical Society.
Abstract Paraffin coatings on glass slides were investigated through both X-ray photoelectron spectroscopy (XPS) and spin relaxation measurement for cesium (Cs) vapor. The components of the glass substrate, such as silicon and oxygen, existed in the XPS spectra of the coated slides, indicating the imperfection of the prepared paraffin coatings. The substrate was not observed after the annealing of the coatings in Cs vapor, which is known as a “ripening” process for spin relaxation measurement. We found a general trend that effective anti-spin relaxation performance requires high paraffin and low Cs coverage on the surface. We also examined a type of diamond-like carbon film, anticipating the effect of anti-spin relaxation; our attempts have failed to date.
I studied the effect of wall collisions on the electron paramagnetic resonance (EPR) of gas phase alkali metal atoms (87Rb). Two types of walls were studied: antirelaxation-coated walls and RbH-coated walls. I measured the dwell times of spin polarized Rb atoms on the two most common antirelaxation coatings, octadecyltrichlorosilane (OTS)- and paraffin. I found that at a cell temperature of 72 C the dwell times for OTS- and paraffin-coated walls are 0.9 ± 0.1 μs and 1.8 ± 0.2 μs, respectively. The implication of these dwell times, which are much longer than what was previously reported in the literature, is discussed in connection with the relaxing property of these coatings. In cells coated with RbH salt I made the first observation of the EPR frequency shift of the gas phase 87Rb atoms. Due to collisions with the RbH salt, which was nuclear spin polarized by spin exchange with optically pumped Rb vapor. The measured EPR frequency shifts are of the order of several hundred Hz in a millimeter-sized cell. By measuring the dependence of the EPR frequency shifts on cell length and by comparing the EPR frequency shifts in RbH-coated cells with those in OTS-coated cells, I provided convincing evidence that the observed EPR frequency shifts are due to collisions with RbH-coated walls, and not due to gas phase processes. The EPR frequency shift is due to the Fermi contact interaction between the s-electron of the adsorbed 87Rb atom and the polarized nucleus on the salt surface. The measured EPR frequency shifts allowed me to calculate the ensemble-averaged phase shift experienced by the Rb atom while adsorbed on the walls. Under our experimental condition this is about 70 mrad. My experiment opens up the possibility of studying surface NMR using gas phase EPR. The phase shift is proportional to the surface nuclear polarization, thus provides an interesting method for measuring the surface nuclear polarization using gas phase EPR. My observation will alert the high precision miniature atomic magnetometry community that collisions with cell walls may cause a systematic error and line broadening in the magnetic resonance frequency.
Observation of nonthermal, light-induced desorption of Cs and Rb atoms from paraffin coating is reported. Buffer-gas-free paraffin-coated cells containing Cs and Rb were exposed to laser light of various intensities and frequencies, and the change of the vapor densities as a function of time was investigated. Because atomic polarization relaxes very slowly in paraffin-coated cells (spin-relaxation times can be $\ensuremath{\gtrsim}1\mathrm{s}),$ they are applied in a variety of precision measurements (e.g., magnetometry, discrete symmetry tests, etc.). Light-induced desorption may be useful in such measurements as a method to control atomic density without changing the temperature of the cell.