48 research outputs found
Manufacturing a thin wire electrostatic trap (TWIST) for ultracold polar molecules
We present a detailed description on how to build a Thin WIre electroStatic
Trap (TWIST) for ultracold polar molecules. It is the first design of an
electrostatic trap that can be superimposed directly onto a magneto optical
trap (MOT). We can thus continuously produce ultracold polar molecules via
photoassociation from a two species MOT and instantaneously trap them in the
TWIST without the need for complex transfer schemes. Despite the spatial
overlap of the TWIST and the MOT, the two traps can be operated and optimized
completely independently due to the complementary nature of the utilized
trapping mechanisms.Comment: 5 pages, 8 figures, updated conten
Trapping of ultracold polar molecules with a Thin Wire Electrostatic Trap
We describe the realization of a dc electric-field trap for ultracold polar
molecules, the thin-wire electrostatic trap (TWIST). The thin wires that form
the electrodes of the TWIST allow us to superimpose the trap onto a
magneto-optical trap (MOT). In our experiment, ultracold polar NaCs molecules
in their electronic ground state are created in the MOT via photoassociation,
achieving a continuous accumulation in the TWIST of molecules in low-field
seeking states. Initial measurements show that the TWIST trap lifetime is
limited only by the background pressure in the chamber.Comment: 4 pages, 3 figure
Formation of ultracold RbCs molecules by photoassociation
The formation of ultracold metastable RbCs molecules is observed in a double
species magneto-optical trap through photoassociation below the
^85Rb(5S_1/2)+^133Cs(6P_3/2) dissociation limit followed by spontaneous
emission. The molecules are detected by resonance enhanced two-photon
ionization. Using accurate quantum chemistry calculations of the potential
energy curves and transition dipole moment, we interpret the observed
photoassociation process as occurring at short internuclear distance, in
contrast with most previous cold atom photoassociation studies. The vibrational
levels excited by photoassociation belong to the 5th 0^+ or the 4th 0^-
electronic states correlated to the Rb(5P_1/2,3/2)+Cs(6S_1/2) dissociation
limit. The computed vibrational distribution of the produced molecules shows
that they are stabilized in deeply bound vibrational states of the lowest
triplet state. We also predict that a noticeable fraction of molecules is
produced in the lowest level of the electronic ground state
Production of ultracold, absolute vibrational ground state NaCs molecules
Thesis (Ph. D.)--University of Rochester. Dept. of Physics and Astronomy, 2013.This dissertation describes a progression of experiments that are based on
the association of ultracold (∼250 μK) Na and Cs atoms with laser light. One of
the primary goals of the experiment is to form molecules in the absolute vibrational
ground state. The work begins with our attempts to label, with certainty,
spectral lines obtained from tuning either the photoassociation (PA formation)
and Resonance Enhanced Multi-Photon Ionization (REMPI detection) lasers. To
this end, we develop a technique that has heretofore never been used in the ultracold
molecule community: pulsed depletion spectroscopy (PDS). Traditionally,
depletion spectroscopy involves the use of narrow-linewidth CW lasers. However,
the narrow linewidth and limited tuning ranges of diodes used for CW depletion
spectroscopy mean that this technique is only helpful if the expected transitions
are known to some degree in advance, and even then is primarily useful for determining
closely-spaced rotational ground state populations. In contrast, the
broad linewidth and flexible tuning range of a pulsed dye laser makes it suitable
for the detection of vibrational progressions, allowing fast determination of
ground state populations even without a priori knowledge of the transitions involved.
We also use this technique in our investigation of excited state potential
energy curves (PECs). We also investigate a range of PA resonances detuned
from the Cs D1 and D2 lines. We find and label PA structure associated with at
least 6, and possibly all 8 electronic states corresponding to both of the Cs 6P
fine structure asymptotes. From the PA and depletion spectra, we obtain information
on the PA scattering process and the excited electronic states. Among
the PA spectra, we find several channels which directly form vibrational ground
state molecules in the singlet electronic state. Finally, we manipulate the internal
states of molecules created with PA using laser light. We use broadband
laser sources to pump higher-lying singlet vibrational levels into the vibrational
ground state. We also find a set of nearly-closed transitions which allow rotational
pumping into the absolute rovibrational ground state
Anti-HCV activity and toxicity of PI4KIIIβ inhibitors
Type III phosphatidylinositol-4-kinase beta (PI4KIIIβ) was previously implicated in hepatitis C virus (HCV) replication by siRNA depletion and was therefore proposed as a novel cellular target for the treatment of hepatitis C. Medicinal chemistry efforts identified highly selective PI4KIIIβ inhibitors that potently inhibited the replication of genotype 1a and 1b HCV replicons and genotype 2a virus in vitro. Replicon cells required more than five weeks to reach low levels of three to five-fold resistance indicating a high resistance barrier to these cellular targets. Extensive in vitro profiling of the compounds revealed a role of PI4KIIIβ in lymphocyte proliferation. Previously proposed functions of PI4KIIIβ in insulin secretion and the regulation of several ion channels were not perturbed with these inhibitors. Moreover, PI4KIIIβ inhibitors were not generally cytotoxic as demonstrated across hundreds of cell lines and primary cells. However, an unexpected anti-proliferative effect in lymphocytes precluded their further development for the treatment of hepatitis C