7 research outputs found
Accurate determination of electric-dipole matrix elements in K and Rb from Stark shift measurements
Stark shifts of potassium and rubidium D1 lines have been measured with high
precision by Miller et al [1]. In this work, we combine these measurements with
our all-order calculations to determine the values of the electric-dipole
matrix elements for the 4p_j-3d_j' transitions in K and for the 5p_j-4d_j'
transitions in Rb to high precision. The 4p_1/2-3d_3/2 and 5p_1/2-4d_3/2
transitions contribute on the order of 90% to the respective polarizabilities
of the np_1/2 states in K and Rb, and the remaining 10% can be accurately
calculated using the relativistic all-order method. Therefore, the combination
of the experimental data and theoretical calculations allows us to determine
the np-(n-1)d matrix elements and their uncertainties. We compare these values
with our all-order calculations of the np-(n-1)d matrix elements in K and Rb
for a benchmark test of the accuracy of the all-order method for transitions
involving nd states. Such matrix elements are of special interest for many
applications, such as determination of magic wavelengths in alkali-metal atoms
for state-insensitive cooling and trapping and determination of blackbody
radiation shifts in optical frequency standards with ions.Comment: 5 page
Visualizing Early Frog Development with Motion-Sensitive 3-D Optical Coherence Microscopy
A motion-sensitive en-face-scanning 3-D optical coherence microscope (OCM) has been designed and constructed to study critical events in the early development of plants and animals. We describe the OCM instrument and present time-lapse movies of frog gastrulation, an early developmental event in which three distinct tissue layers are established that later give rise to all major organ systems. OCM images constructed with fringe-amplitude data show the mesendoderm migrating up along the blastocoel roof, thus forming the inner two tissue layers. Motion-sigma data, measuring the random motion of scatterers, is used to construct complementary images that indicate the presence of Brownian motion in the yolk cells of the endoderm. This random motion provides additional intrinsic contrast that helps to distinguish different tissue types. Depth penetration at 850 nm is sufficient for studies of the outer ectoderm layer, but is not quite adequate for detailed study of the blastocoel floor, about 500 to 800 μm deep into the embryo. However, we measure the optical attenuation of these embryos to be about 35% less at 1310 nm. 2-D OCT images at 1310 nm are presented that promise sufficient depth penetration to test current models of cell movement near the blastocoel floor during gastrulation
Improved signal-to-noise ratio in spectral-domain compared with time-domain optical coherence tomography
Studium der Nukleon- und Kernstruktur durch tiefinelastische Myonenstreuung
Available from TIB Hannover: D.Dt.F. QN1(4,51) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman