Hyperfine spectroscopy and laser cooling of the fermionic isotopes ${}^{47}$Ti and ${}^{49}$Ti

Abstract

We report on magneto-optical trapping of the two fermionic isotopes of atomic titanium, ${}^{47}$Ti and ${}^{49}$Ti. Unlike the even mass-number isotopes, which were recently laser cooled, ${}^{47}$Ti and ${}^{49}$Ti have nonzero nuclear spins and, consequently, their atomic levels are split by hyperfine structure. Combining and comparing theoretical calculations and atomic beam-spectroscopy measurements, we determine the hyperfine structures and isotope shifts of the $3{\mathrm{d}}^{2}4{\mathrm{s}}^2$ ${\mathrm{a}}^3{\mathrm{F}}_4\to 3{\mathrm{d}}^2{(}^3\mathrm{P})4s4p{(}^3{\mathrm{P}}^{\mathrm{o}})$ ${\mathrm{y}}^5{\mathrm{D}}_4^{\mathrm{o}}$ optical-pumping transition at optical wavelength 391nm and the $3{\mathrm{d}}^3{(}^4\mathrm{F})4s$ ${\mathrm{a}}^5{\mathrm{F}}_5\to 3{\mathrm{d}}^3{(}^4\mathrm{F})4p$ ${\mathrm{y}}^5{\mathrm{G}}_6^{\mathrm{o}}$ laser-cooling transition at wavelength 498nm. With this information, we produce magneto-optical traps of both ${}^{47}$Ti and ${}^{49}$Ti by applying two additional tones of light to repump atoms to the maximum-spin states on the laser-cooling transition. Directly loading from the atomic flux of a titanium sublimation pump, we produce ${}^{47}$Ti and ${}^{49}$Ti traps with 731(190) and 1142(240) atoms, and with lifetimes of 330(15)ms and 310(8)ms, respectively.