2,715 research outputs found
Continuous wave detector has wide frequency range
Portable battery-operated detector indicates the presence of steady state signals exceeding a predetermined value over a wide frequency range by the closure of output relay contacts. It was designed to monitor electronic equipment used in the Saturn 2 program
Solvent promoted reversible cyclometalation in a tethered NHC iridium complex
Reaction of [Ir(COD)(pyâItBu)]+ (pyâItBu = 3-tert-butyl-1-picolylimidazol-2-ylidene) with acetonitrile results in reversible intramolecular CâH bond activation of the NHC ligand and formation of [Ir(η2:η1-C8H13)(pyâItBuâČ)(NCMe)]+. Coordinated COD acts as an internal hydride acceptor and acetonitrile coordination offsets the otherwise unfavourable thermodynamics of the process
Relationship between the Linear Ringing Frequencies in 3He-A and 3He-B near the Polycritical Point
New measurements of parallel ringing in a quasi-ideal geometry for 3He-B near the temperature and pressure of the polycritical point suggest fB2/fA2âŒ5/2, where fB and fA are the linear parallel-ringing frequencies at a given temperature near Tc. This result approaches the prediction of theory using the Anderson-Brinkman-Morel and Balian-Werthamer states to describe 3He-A and 3He-B, respectively, and hence the results of Osheroff at melting pressure, but disagrees with earlier observations at pressures near the polycritical point
Relaxation of the Wall-Pinned Magnetization Ringing Mode in Superfluid 3He-B
Observations of the wall-pinned mode in 3He-B allow new magnetic relaxation phenomena to be studied. Excepting the quantitative value of the zero-time ringing frequency, comparison of experiment with theory is satisfactory, including a linear dependence of the square of the ringing period on time and a square-root singularity near Tc in the relaxation parameter
Nonlinear Parallel Ringing of Magnetization in Superfluid 3He
Experiments based on an analogy to the ac Josephson effect have shown in both 3He-A and 3He-B that a pairing theory of the superfluidity of 3He is essentially correct. Additional observations of parallel ringing are not in agreement with the simple pendulum models used to describe nonlinear dynamic magnetic effects
Thermodynamically consistent equilibrium properties of normal-liquid Helium-3
The high-precision data for the specific heat C_{V}(T,V) of normal-liquid
Helium-3 obtained by Greywall, taken together with the molar volume V(T_0,P) at
one temperature T_0, are shown to contain the complete thermodynamic
information about this phase in zero magnetic field. This enables us to
calculate the T and P dependence of all equilibrium properties of normal-liquid
Helium-3 in a thermodynamically consistent way for a wide range of parameters.
The results for the entropy S(T,P), specific heat at constant pressure
C_P(T,P), molar volume V(T,P), compressibility kappa(T,P), and thermal
expansion coefficient alpha(T,P) are collected in the form of figures and
tables. This provides the first complete set of thermodynamically consistent
values of the equilibrium quantities of normal-liquid Helium-3. We find, for
example, that alpha(T,P) has a surprisingly intricate pressure dependence at
low temperatures, and that the curves alpha(T,P) vs T do not cross at one
single temperature for all pressures, in contrast to the curves presented in
the comprehensive survey of helium by Wilks.
Corrected in cond-mat/9906222v3: The sign of the coefficient d_0 was
misprinted in Table I of cond-mat/9906222v1 and v2. It now correctly reads
d_0=-7.1613436. All results in the paper were obtained with the correct value
of d_0. (We would like to thank for E. Collin, H. Godfrin, and Y. Bunkov for
finding this misprint.)Comment: 19 pages, 19 figures, 9 tables; published version; note added in
proof; v3: misprint correcte
Adaptive Optical Phase Estimation Using Time-Symmetric Quantum Smoothing
Quantum parameter estimation has many applications, from gravitational wave
detection to quantum key distribution. We present the first experimental
demonstration of the time-symmetric technique of quantum smoothing. We consider
both adaptive and non-adaptive quantum smoothing, and show that both are better
than their well-known time-asymmetric counterparts (quantum filtering). For the
problem of estimating a stochastically varying phase shift on a coherent beam,
our theory predicts that adaptive quantum smoothing (the best scheme) gives an
estimate with a mean-square error up to times smaller than that
from non-adaptive quantum filtering (the standard quantum limit). The
experimentally measured improvement is
Concentration Dependence of the Effective Mass of He-3 Atoms in He-3/He-4 Mixtures
Recent measurements by Yorozu et al. (S. Yorozu, H. Fukuyama, and H.
Ishimoto, Phys. Rev. B 48, 9660 (1993)) as well as by Simons and Mueller (R.
Simons and R. M. Mueller, Czhechoslowak Journal of Physics Suppl. 46, 201
(1976)) have determined the effective mass of He-3 atoms in a He-3/He-4 mixture
with great accuracy. We here report theoretical calculations for the dependence
of that effective mass on the He-3 concentration. Using correlated basis
functions perturbation theory to infinite order to compute effective
interactions in the appropriate channels, we obtain good agreement between
theory and experiment.Comment: 4 pages, 1 figur
Efficient two-step access to azafluorenones and related compounds
International audienceCrystals of a lithiocuprate prepared from copper(I) chloride and lithium 2,2,6,6-tetramethylpiperidide (2 equiv) were isolated and analyzed by X-ray diffraction as (TMP)2Cu(Cl)Li2*THF. The observation of this species is consistent with its having a role in deprotocupration-aroylation. Phenyl pyridyl ketones, phenyl quinolyl ketones, and phenyl thienyl ketones were prepared in tetrahydrofuran using the lithiocuprate and aroyl chorides as electrophiles. Diaryl ketones bearing a chloro group at the 2 position (of a pyridyl or phenyl group) thus synthesized were next converted through palladium-catalyzed ring closure to polycycles of the 5H-indeno[1,2-b]pyridin-5-one, 11H-indeno[1,2-b]quinolin-11-one, 9H-indeno[2,1-c]pyridin-9-one, and 8H-indeno[2,1-b]thiophen-8-one families
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