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We have developed a source of cold LiH molecules for Stark deceleration and trapping experiments. Lithium metal is ablated from a solid target into a supersonically expanding carrier gas. The translational, rotational, and vibrational temperatures are 0.9±0.1, 5.9±0.5, and 468±17 K, respectively. Although they have not reached thermal equilibrium with the carrier gas, we estimate that 90% of the LiH molecules are in the ground state, X 1Σ+(v=0,J=0). With a single 7 ns ablation pulse, the number of molecules in the ground state is 4.5±1.8×107 molecules\sr. A second, delayed, ablation pulse produces another LiH beam in a different part of the same gas pulse, thereby almost doubling the signal. A long pulse, lasting 150 μs, can make the beam up to 15 times more intense. [ABSTRACT FROM AUTHOR]

We report the first laser-radio-frequency double resonance spectrum of a simple lanthanide compound, the paramagnetic radical 174YbF. Measurements of the rf intervals as a function of the rotational quantum number N allow us to determine precise spin-rotation and fluorine hyperfine interaction coupling constants for the X 2Σ+(v=0 and v=1) ground states of 174YbF. The results for v=0 are γ0=-13.424 00(16) MHz, γ1=3.982 3(11) kHz, γ2=-25(1) mHz, b0=141.795 6(5) MHz, b1=-0.510(11) kHz, c=85.402 6(14) MHz, C=20.38(13) kHz. For v=1 they are γ0=-33.811 8(7) MHz, γ1=4.323(6) kHz, γ2=-28(9) mHz, b0=139.89(4) MHz, b1=-0.7(4) kHz, c=86.75(5) MHz, C=18.3(1) kHz. A direct microwave measurement of the first rotational interval in X 2Σ+(v=0) gives the rotational constant B0=0.241 292 7(7) cm-1. Finally, the Stark shift of hyperfine transitions in the first two rotational states of X 2Σ+(v=0) are analyzed to determine the electric dipole moment μe=3.91(4) D. We find that although the gross structure of YbF in its ground state resembles that of an alkaline earth monofluoride, the 4f shell is evidently important even in the low-lying excited states and leads to unusual behavior in the ground-state magnetic structure. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We report measurements and calculations of x-ray diffuse scattering from the liquid–vapor interface of toluene and polybromostyrene(PBrS)/toluene solutions for polymer molecular weights 90 K and 1 M at concentrations up to 11.7 volume %, well into the entangled semidilute regime. We have calculated the static structure factor S(k) and equal time height–height correlation function C(R) for surface hydrodynamic modes based on a coupled two-fluid model where the polymer response is taken to be that of a Maxwell viscoelastic material [Harden et al., J. Chem. Phys. 94, 5208 (1991)]. We obtain the leading correction term to the capillary-wave result for C(R) dependent on the solution shear modulus E0, as well as an analytic approximation valid for large E0, including the case of pure polymer melt. [ABSTRACT FROM AUTHOR]

`Finley' hard red winter wheat (Triticum aestivum L.) (Reg. no. CV-881, PI 586757) was developed by the Agricultural Research Center of Washington State University in cooperation with the USDA-ARS. Finley [...]

We have measured the Stark shift of the A ²II½-X ²Σ+ transition in YbF. We use a molecular beam triple resonance method, with two laser transitions acting as pump and probe, assisted by an rf transition that tags a single hyperfine transition of the X state. After subtracting the known ground state Stark shift, we obtain a value of 70.31.5 Hz/ V/cm² for the static electric polarizability of the state A² ½ (J=½,f) by fitting our data to a purely quadratic Stark shift in the interval 0-5 kV/cm. A more exact analysis that does not assume a perfectly quadratic Stark effect yields the value μe=2.483 D for the electric dipole moment of the A ² II½ (v=0) state. [ABSTRACT FROM AUTHOR]

Experiments with cold molecules usually begin with a molecular source. We describe the construction and characteristics of a cryogenic buffer gas source of CaF molecules. The source emits pulses with a typical duration of 240 s, a mean speed of about 150 m/s, and a flux of molecules per steradian per pulse in a single rotational state. [ABSTRACT FROM AUTHOR]