@article{ee70df83668e4d00baf7937502d50a6f,
title = "Testing the effect of surface coatings on alkali atom polarization lifetimes",
abstract = "The evaluation of different surface coatings used in alkali metal atomic magnetometers is necessary for the improvement of sensitivity of these devices. A method to measure the polarization lifetime of alkali atoms in the region between substrates with different coatings was developed to determine the effectiveness of the coating at preserving alkali spin polarization as well as chemical compatibility and higherature stability. Multiple coatings can be compared under identical experimental conditions, using an experimental geometry that allows surface characterization before and after evaluation of the polarization lifetime. Multilayered, cross-linked octadecyltrichlorosilane films, alkyltrichlorosilane monolayers, and octadecylphosphonic acid monolayers were evaluated using this approach.",
author = "Seltzer, {S. J.} and Rampulla, {D. M.} and S. Rivillon-Amy and Chabal, {Y. J.} and Bernasek, {S. L.} and Romalis, {M. V.}",
note = "Funding Information: This work was supported by an Office of Naval Research MURI Grant No. SA4845-10556. The authors thank Dima Budker, Jeffrey Schwartz, Joe Dennes, and Amber Hibberd for helpful discussions, and Ken Andreas and Mike Souza for help in the construction of the alkali cell. FIG. 1. Setup of the polarization lifetime measurement. Nearly-parallel resonant pump and probe beams perform a relaxation-in-the-dark measurement of the polarization lifetime T 1 as pumping is modulated by an optical chopper. A supply of purified helium and a vacuum pump allow control of the buffer gas pressure in the cell. FIG. 2. (a) Polarization data taken at 80 Torr of He that correspond to the data point along the 125 bounces curve shown in (c). (b) Enlarged portion of the data from (a) that shows the fitted curve (light gray, red online) of the sum of two decaying exponentials to extract T 1 . (c) Measurements of alkali polarization lifetimes as a function of buffer gas pressure, compared to values predicted by a mathematical model. The lifetime allowed by uncoated surfaces agrees with the model{\textquoteright}s prediction for a completely depolarizing surface, while measurements for thick, cross-linked OTS samples agree with predictions for surfaces allowing several hundred bounces. FIG. 3. IR spectroscopy of an OTS monolayer. Indicating the presence of a well-ordered monolayer, DTS and OTS monolayers exhibited similar spectral features at ∼ 2920 cm − 1 (asymmetric C-H vibrational mode) and ∼ 2850 cm − 1 (symmetric C-H vibrational mode). The minimal changes in spectral features upon exposure of the film to K vapor indicate that the film remains intact. FIG. 4. Reversible temperature dependence of T 1 , DTS . Data 1 is the first measurement at 65 ° C , data 2 is at 95 ° C , data 3 is cooling to 65 ° C , and data 4 and 5 subsequent heating and cooling to 95 and 65 ° C . Individual data points in each numbered group are repeated measurements with the indicated temperature held constant. ",
year = "2008",
doi = "10.1063/1.2985913",
language = "English (US)",
volume = "104",
journal = "Journal of Applied Physics",
issn = "0021-8979",
publisher = "American Institute of Physics Publising LLC",
number = "10",
}