Refractive Index of Gaseous and Liquid Hydrogen

摘要

The refractive index of gaseous and liquid hydrogen has been measured by an interferometric method at temperatures between 15deg; and 298.15deg;K and at pressures up to 230 atm. The measurements have been analyzed in terms of the density and temperature dependence of the Lorentzndash;Lorenz function,Lsngbnd;Lthinsp;equiv;thinsp;lsqb;lpar;nlgr;2thinsp;minus;thinsp;1rpar;thinsp;sol;thinsp;lpar;nlgr;2thinsp;plus;thinsp;2rpar;rsqb;rgr;minus;1, wherenlgr;is the refractive index atlgr;thinsp;equals;thinsp;5462 Aring;andrgr;is the fluid density in grams per cubic centimeter. The precision and reproducibility of Lsngbnd;L is better than 0.05percnt; in most cases. Lsngbnd;L for gaseous parahydrogen first increases with increasing density to a maximum and then decreases to values below the lowhyphen;density limit. Lsngbnd;L is also slightly temperature dependent; the lowhyphen;density limit increases with increasing temperature; the maximum on the Lsngbnd;L isotherms decreases with increasing temperature. Lsngbnd;L for saturated liquid parahydrogen decreases with increasing density by about 0.1percnt; at temperatures between 15deg; and 32deg;K. The difference in Lsngbnd;L for normal and parahydrogen is consistent with previous theoretical and experimental estimates of the molecularhyphen;polarizability difference.