High-resolution photoassociation spectroscopy of the6Li213Σ

Abstract

We present experimental observations of seven vibrational levels v = 20 − 26 of the 1 3 Σ + g excited state of Li2 molecules by the photoassociation (PA) of a degenerate Fermi gas of 6 Li atoms. For each vibrational level, we resolve the rotational structure using a Feshbach resonance to enhance the PA rates from p-wave collisions. We also, for the first time, determine the spin-spin and spin-rotation interaction constants for this state. The absolute uncertainty of our measurements is ±0.00002 cm −1 (±600 kHz). We use these new data to further refine an analytic potential for this state.

LEVEL: A computer program for solving the radial Schrödinger equation for bound and quasibound levels

“…(20), but could take on any form predicted by theory. In particular, in the present version of LEVEL it may be represented as one of the roots of a 2 Â 2 or 3 Â 3 diagonalization arising from the type of two-state [33,49] or three-state [50,51] coupling encountered for alkali dimers at the first nS þnP asymptote [44]. A more detailed discussion of various features of the MLR potential function forms may be found in Ref.…”

High-resolution photoassociation spectroscopy of the6Li2A(11Gunton1, Semczuk2, Dattani3 et al. 2013Phys. Rev. ASelf Cite181280View full textAdd to dashboardCite

“…The number of atoms remaining in the CDT is determined by an absorption image of the cloud. The Ti:sapphire laser is stabilized to a fiber-based, self-referenced frequency comb [12,19] and, after stabilization, it has an absolute frequency uncertainty of ±600 kHz. We observe the PA spectrum for seven vibrational levels (v = 29-35) of the A(1 1 + u ) state which arise from s-wave collisions between atoms in states |1 and |2 ; see Table I.…”

“…To interpret our results, we first consider the allowed quantum numbers for the initial and final states of the colliding complex (see [12] for a more detailed explanation). The initial unbound molecular state can be labeled by |N,G,f 1 ,f 2 , where f m = s m + i m is the total angular momentum of the mth atom (m = 1,2).…”

“…First, as p-wave (and higher-order) collisions are greatly suppressed at ultracold temperatures only the excited state N = 1 rotational level is relevant for photoassociation. Second, the thermal broadening at ultracold temperatures is far below the natural linewidth of these transitions and therefore the frequency of the transition should be known at a precision at or below this linewidth.Our apparatus and experimental method is described in detail in [12,18]. Briefly, for these photoassociation measurements, we prepare our ensemble by loading a magneto-optical trap (MOT) with 2 × 10 7 6 Li atoms and transferring them into a crossed optical dipole trap (CDT).…”

“…Our apparatus and experimental method is described in detail in [12,18]. Briefly, for these photoassociation measurements, we prepare our ensemble by loading a magneto-optical trap (MOT) with 2 × 10 7 6 Li atoms and transferring them into a crossed optical dipole trap (CDT).…”