We measured the rate of velocity-changing collisions (VCCs) between alkali atoms and background gas in buffer-gas-free anti-spin-relaxation-coated cells. The average VCC rate in paraffin-coated rubidium vapor cells prepared in this work was $1 \times 10^{6}$ s $^{-1}$ , which corresponds to $\sim$1 mm in the mean free path of rubidium atoms. This short mean free path indicates that alkali atoms do not travel freely between the cell walls. In addition, we found that a heating process known as increases the VCC rate, and also confirmed that ripening improves the anti-relaxation performance of the coatings.We measured the rate of velocity-changing collisions (VCCs) between alkali atoms and background gas in buffer-gas-free anti-spin-relaxation-coated cells. The average VCC rate in paraffin-coated rubidium vapor cells prepared in this work was $1 \times 10^{6}$ s$^{-1}$, which corresponds to $\sim$1 mm in the mean free path of rubidium atoms. This short mean free path indicates that alkali atoms do not travel freely between the cell walls. In addition, we found that a heating process known as increases the VCC rate, and also confirmed that ripening improves the anti-relaxation performance of the coatings.

Oct 20, 20150 citations

Surface coatings for atomic magnetometry

Scott J. Seltzer, Marie-Anne Bouchiat, M. V. Balabas

Introduction and history Paraffin films and other surface coatings have played a decisive role in the emergence and development of optical magnetometry. When alkali atoms in the vapor phase collide with the bare surface of a glass container, they disappear inside the glass and are replaced in the vapor phase by another atom with random spin orientation. With a mean free path of the dimensions of the cell (typically on the order of 1 to several cm), the collision frequency is much too high, 10 4 s −1 , to maintain the substantial spin polarization required for practical applications. In order to prevent this detrimental effect, vapor cells include either an inert buffer gas [1–3] or an antirelaxation surface coating [4]. In the presence of a noble gas at a pressure from 10 −2 to a few atmospheres, the alkali atoms diffuse very slowly from the center of the cell to the glass walls, and their orientation is only very slightly affected by gas collisions. However, there are several advantages to the use of a surface coating instead of buffer gas. If the static magnetic field is not homogeneous, then resonance lines suffer from inhomogeneous broadening in the presence of the gas [5–7]. In addition, the optical pumping process is perturbed by the buffer gas [8, 9]: (i) it is more efficient at the center of the cell than near the uncoated walls, so that the atomic orientation is inhomogeneous inside the cell; (ii) the pump beam absorption line is broadened, and its profile varies with the distance from the entrance window. These effects are unfavorable for the production of alignment in the ground state.Introduction and history Paraffin films and other surface coatings have played a decisive role in the emergence and development of optical magnetometry. When alkali atoms in the vapor phase collide with the bare surface of a glass container, they disappear inside the glass and are replaced in the vapor phase by another atom with random spin orientation. With a mean free path of the dimensions of the cell (typically on the order of 1 to several cm), the collision frequency is much too high, 10 4 s −1 , to maintain the substantial spin polarization required for practical applications. In order to prevent this detrimental effect, vapor cells include either an inert buffer gas [1–3] or an antirelaxation surface coating [4]. In the presence of a noble gas at a pressure from 10 −2 to a few atmospheres, the alkali atoms diffuse very slowly from the center of the cell to the glass walls, and their orientation is only very slightly affected by gas collisions. However, there are several advantages to the use of a surface coating instead of buffer gas. If the static magnetic field is not homogeneous, then resonance lines suffer from inhomogeneous broadening in the presence of the gas [5–7]. In addition, the optical pumping process is perturbed by the buffer gas [8, 9]: (i) it is more efficient at the center of the cell than near the uncoated walls, so that the atomic orientation is inhomogeneous inside the cell; (ii) the pump beam absorption line is broadened, and its profile varies with the distance from the entrance window. These effects are unfavorable for the production of alignment in the ground state.

Cambridge University Press eBooksMar 7, 20136 citations

Low-energy collisions between alkali and rare-gas atoms

G. Peach

Physics of Electronic and Atomic Collisions: ICPEAC XIJan 1, 19790 citations

A simplified model for cold collisions of alkali atoms

J. M. M. J. Vogels, B. Verhaar, R. H. Blok

Bulletin of the American Physical SocietyMay 1, 19980 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.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 AOct 23, 2002154 citations

1 \times 10^{6}

^{-1}

, which corresponds to $\sim$1 mm in the mean free path of rubidium atoms. This short mean free path indicates that alkali atoms do not travel freely between the cell walls. In addition, we found that a heating process known as increases the VCC rate, and also confirmed that ripening improves the anti-relaxation performance of the coatings.