The Electric Dipole Moment of the B(1)Pi State of ZrO

A laser ablation source combined with a time-of-flight mass spectrometer has been constructed. The static electric field in the mass spectrometer gives rise to a first-order Stark effect splitting from which the permanent electric dipole moment of the B(1)Pi state (v = 0) of (90)ZrO is determined and found to be 3.43 +/- 0.07 D. The X(1)Sigma and B(1)Pi states are further investigated and comparisons with the results from ab initio calculations are made. Copyright 2000 Academic Press.     

激光冷却SH~–阴离子的理论研究

本文采用多组态相互作用及Davidson修正方法和全电子基组计算了SH~-阴离子的X~1∑~+,a~3∏和A~1∏态的势能曲线、电偶极矩和跃迁偶极矩.计算的光谱常数与实验值及已有的理论值符合得很好.在计算中考虑了自旋-轨道耦合效应.计算得到a~3∏_1(v'=0)?X~1∑_(0+)~+(v"=0)和A~1∏_1(v'=0)?X~1Σ_(0+)~+(v"=0)跃迁具有高对角分布的弗兰克-康登因子,分别为0.9990和0.9999;计算得到a~3∏_1和A~1∏_1态的自发辐射寿命分别为1.472和0.188 ms.A~1∏_1?X~1∑_(0+)~+跃迁存在中间态a~3∏_(0+)和a~3∏_1,但中间态对激光冷却SH~-阴离子的影响可以忽略.分别利用a~3∏_1(v'=0)? X~1∑_(0+)~+(v"=0)和A~1∏_1(v'=0)? X~1∑_(0+)~+(v"=0)跃迁构建了准闭合的能级系统,冷却所需的激光波长分别为492.27和478.57 nm.最后预测了激光冷却SH~-阴离子能达到的多普勒温度和反冲温度.这些结果为进一步实验提供了理论参数.     

Spectroscopic study of B2Σ+–X1 2Π1/2 transition of electron electric dipole moment candidate PbF

PbF, a valuable candidate for measuring the electron electric dipole moment (eEDM), is of great significance in measuring its spectrum and deriving its molecular constants in experiment. In the present work, the rovibronic spectrum of the B$^{2}{\Sigma }^{+}$-X$_{1}^{\, 2}{\Pi }_{1/2}$ transition of PbF in a wavelength range of 260 nm-285 nm is studied by the laser ablation/laser induced fluorescence method. The molecular parameters of the X$_{1}^{\, 2}{\Pi }_{1/2}$ (${v'}=0)$ and B$^{2}{\Sigma }^{+}$ (${v}'=0, 1$) states are derived from the recorded spectra of the (0, 0) and (1, 0) bands of the B$^{2}{\Sigma }^{+}$-X$_{1}^{\, 2}{\Pi }_{1/2}$ transition. Also, the Franck-Condon factors (FCFs) of the transitions between the B$^{2}{\Sigma }^{+}$ and X$_{1}^{\, 2}{\Pi }_{1/2}$ states are calculated by the RKR/LEVEL method and the Morse potential method, respectively.     

Fourier Transform Spectroscopy of the A'(1)Pi-X(1)Sigma(+) System of CaO

The A'(1)Pi-X(1)Sigma(+) near-infrared system of CaO was observed for the first time at high resolution using a Fourier transform spectrometer. The A'(1)Pi-X(1)Sigma(+) chemiluminescence was excited in a Ca + N(2)O flame produced in a Broida-type oven. More than 3000 rotational lines, classified into 19 bands involving the A'(1)Pi 0 /= 2) levels with the nearby b(3)Sigma(+) (v-2) levels has been detected. An extended set of A'(1)Pi (v = 0-3) data has been obtained which is suitable for use in a future multistate deperturbation analysis of the a(3)Pi approximately A'(1)Pi approximately b(3)Sigma(+) approximately A(1)Sigma(+) complex of excited states. The new near-infrared spectra of the A'(1)Pi-X(1)Sigma(+) transition of CaO also permits the first direct high-resolution linkage between the orange and green systems and the near-infrared bands. Copyright 2000 Academic Press.     

Parity-violating neutron spin rotation in hydrogen and deuterium

We calculate the (parity-violating) spin-rotation angle of a polarized neutron beam through hydrogen and deuterium targets, using pionless effective field theory up to next-to-leading order. Our result is part of a program to obtain the five leading independent low-energy parameters that characterize hadronic parity violation from few-body observables in one systematic and consistent framework. The two spin-rotation angles provide independent constraints on these parameters. Our result for np spin rotation is $\frac{1} {\rho }\frac{{d\varphi _{PV}^{np} }} {{dl}} = \left[ {4.5 \pm 0.5} \right] rad MeV^{ - \frac{1} {2}} \left( {2g^{\left( {^3 S_1 - ^3 P_1 } \right)} + g^{\left( {^3 S_1 - ^3 P_1 } \right)} } \right) - \left[ {18.5 \pm 1.9} \right] rad MeV^{ - \frac{1} {2}} \left( {g_{\left( {\Delta {\rm I} = 0} \right)}^{\left( {^1 S_0 - ^3 P_0 } \right)} - 2g_{\left( {\Delta {\rm I} = 2} \right)}^{\left( {^1 S_0 - ^3 P_0 } \right)} } \right)$\frac{1} {\rho }\frac{{d\varphi _{PV}^{np} }} {{dl}} = \left[ {4.5 \pm 0.5} \right] rad MeV^{ - \frac{1} {2}} \left( {2g^{\left( {^3 S_1 - ^3 P_1 } \right)} + g^{\left( {^3 S_1 - ^3 P_1 } \right)} } \right) - \left[ {18.5 \pm 1.9} \right] rad MeV^{ - \frac{1} {2}} \left( {g_{\left( {\Delta {\rm I} = 0} \right)}^{\left( {^1 S_0 - ^3 P_0 } \right)} - 2g_{\left( {\Delta {\rm I} = 2} \right)}^{\left( {^1 S_0 - ^3 P_0 } \right)} } \right), while for nd spin rotation we obtain $\frac{1} {\rho }\frac{{d\varphi _{PV}^{nd} }} {{dl}} = \left[ {8.0 \pm 0.8} \right] rad MeV^{ - \frac{1} {2}} g^{\left( {^3 S_1 - ^1 P_1 } \right)} + \left[ {17.0 \pm 1.7} \right] rad MeV^{ - \frac{1} {2}} g^{\left( {^3 S_1 - ^3 P_1 } \right)} + \left[ {2.3 \pm 0.5} \right] rad MeV^{ - \frac{1} {2}} \left( {3g_{\left( {\Delta {\rm I} = 0} \right)}^{\left( {^1 S_0 - ^3 P_0 } \right)} - 2g_{\left( {\Delta {\rm I} = 1} \right)}^{\left( {^1 S_0 - ^3 P_0 } \right)} } \right)$\frac{1} {\rho }\frac{{d\varphi _{PV}^{nd} }} {{dl}} = \left[ {8.0 \pm 0.8} \right] rad MeV^{ - \frac{1} {2}} g^{\left( {^3 S_1 - ^1 P_1 } \right)} + \left[ {17.0 \pm 1.7} \right] rad MeV^{ - \frac{1} {2}} g^{\left( {^3 S_1 - ^3 P_1 } \right)} + \left[ {2.3 \pm 0.5} \right] rad MeV^{ - \frac{1} {2}} \left( {3g_{\left( {\Delta {\rm I} = 0} \right)}^{\left( {^1 S_0 - ^3 P_0 } \right)} - 2g_{\left( {\Delta {\rm I} = 1} \right)}^{\left( {^1 S_0 - ^3 P_0 } \right)} } \right), where the g ^(X-Y), in units of $MeV^{ - \frac{3} {2}}$MeV^{ - \frac{3} {2}}, are the presently unknown parameters in the leading-order parity-violating Lagrangian. Using naıve dimensional analysis to estimate the typical size of the couplings, we expect the signal for standard target densities to be $\left| {\frac{{d\varphi _{PV} }} {{dl}}} \right| \approx \left[ {10^{ - 7} \ldots 10^{ - 6} } \right]\frac{{rad}} {m}$\left| {\frac{{d\varphi _{PV} }} {{dl}}} \right| \approx \left[ {10^{ - 7} \ldots 10^{ - 6} } \right]\frac{{rad}} {m} for both hydrogen and deuterium targets. We find no indication that the nd observable is enhanced compared to the np one. All results are properly renormalized. An estimate of the numerical and systematic uncertainties of our calculations indicates excellent convergence. An appendix contains the relevant partial-wave projectors of the three-nucleon system.     

Laser-Excited Fluorescence Spectra of Strontium Monoiodide

Fluorescence spectra of strontium monoiodide excited by Ar++ and Kr+ laser lines have been analyzed by Fourier transform spectrometry. Rotational levels have been populated either directly or after collisional relaxation: (i) in D2Sigma+ (v = 0, 1) by ultraviolet lines of Ar++, inducing numerous fluorescence transitions ending in the levels v = 0-3 of the strongly interacting A2Pi and B2Sigma+ states, (ii) in A2Pi3/2 (v = 0-4) by Kr+ line at 676.44 nm, de-exciting into transitions to X2Sigma+ (v = 0-6). Deperturbed constants for A2Pi and B2Sigma+ states and A approximately B interaction parameter are calculated from the numerical treatment of D2Sigma+ (v = 0, 1) --> A2Pi (v = 0-3) approximately B2Sigma+ (v = 0-3) transitions. Rotational constants for D2Sigma+ (v = 0, 1) are obtained for the first time. The wavenumbers of some 670 fluorescence lines are cataloged. Copyright 1999 Academic Press.     

Formation of ultracold polar molecules via Raman excitation

Alkali hydride molecules are very polar, exhibiting large ground-state dipole moments. As ultracold sources of alkali atoms, as well as hydrogen, have been created in the laboratory, we explore theoretically the feasibility of forming such molecules from a mixture of the ultracold atomic gases, employing a two-photon stimulated radiative association process -- Raman excitation. Using accurate molecular potential energy curves and dipole transition moments, we have calculated the rate coefficients for populating all the vibrational levels of the X state of LiH via the excited A state. We have found that significant molecule formation rates can be realized with laser intensities and atomic densities that are attainable experimentally. Because of the large X state dipole moment, rapid cascade occurs down the ladder of vibrational levels to v = 0. The calculated recoil momentum imparted to the molecule is small, and thus negligible trap loss results from the cascade process. This allows for the build-up of a large population of v = 0 trapped molecules.Received: 31 August 2004, Published online: 23 November 2004PACS: 34.50.Rk Laser-modified scattering and reactions - 32.80.Pj Optical cooling of atoms; trapping - 33.20.Vq Vibration-rotation analysis     

High-Resolution Fourier Transform Emission Spectroscopy of the B(2)Sigma(+) (v = 0)-X(2)Sigma(+) (v = 0) Transition of the PN(+) Ion

Ultraviolet emission spectrum of the B(2)Sigma(+) (v = 0)-X(2)Sigma(+) (v = 0) transition of the PN(+) ion has been observed at a resolution of 0.05 cm(-1) by a Fourier transform spectrometer. The rotational analysis led to a great improvement of rotational constants in the B(2)Sigma(+) (v = 0) and X(2)Sigma(+) (v = 0) states as well as to the first determination of centrifugal distortion constants for both levels and spin-rotation interaction constant in the X(2)Sigma(+) (v = 0) state. Rotational perturbation in the B(2)Sigma(+) (v = 0) state was observed. Copyright 2000 Academic Press.     

The (1)(3)Pi Electronic State of LaF

Rotational studies of bands of the infrared systems (1)(3)Pi-->(1)(3)Delta and (1)(3)Pi(1)-->X(1)Sigma(+) of lanthanum monofluoride were carried out with the aim of characterizing the (1)(3)Pi state, assuming the previous representations of X(1)Sigma(+) and (1)(3)Delta (1-3). The vibrational levels of (1)(3)Pi involved in the analyzed transitions were v=0, 1, 2 of the Omega=0 component, v=0, 1 of the Omega=1 component, and v=0 of the Omega=2 component. Perturbations were observed in both systems which were ascribed to spin-uncoupling interactions between (1)(3)Pi(2)(v=0) and (1)(3)Pi(1)(v=1) levels. A 9x9 matrix representation at equilibrium of the complex of interacting levels (v=0, 1, 2) was constructed, each diagonal v-block corresponding to a triplet model of the rovibrational (3)Pi Hamiltonian. The wavenumbers of some 1910 lines in the two systems were simultaneously fitted (rms error of the fit of about 0.0053 cm(-1)), thus yielding a consistent set of accurate spectroscopic constants for the (1)(3)Pi state; the spin-uncoupling interaction parameter was determined as B(Pi)(0, 1)=0.010917(13) cm(-1). Copyright 2001 Academic Press.     

Characterization of the Ground State of Br(2) by Laser-Induced Fluorescence Fourier Transform Spectroscopy of the B(3)Pi(0(+))(u)-X(1)Sigma(+)(g) System

The laser-induced fluorescence (LIF) spectrum of the B(3)Pi(0(+))(u)-X(1)Sigma(+)(g) system of Br(2) was recorded by Fourier transform spectroscopy (FTS). The LIF spectra were obtained by using continuous-wave dye laser excitation in the spectral region 16 800-18 000 cm(-1). About 1800 rotationally resolved lines were recorded in 96 fluorescence progressions, originating from the 10 相似文献   

~(39)K_2分子C~1Ⅱ_u-X~1∑_9~+(J′=105)Q支激光诱导荧光光谱及电偶极跃迁矩变化率研究

用4415.6(?)CW激光线获得了~(39)K_2分子C~1II_u(v′=0,J′=105)-X~1∑_g~+(v″=1～10,J″=105)Q支激光诱导荧光(LIF)光谱.用最小二乘法拟合出了~(39)K_2分子X~1∑_g~+态振动常数和C~1II_u态电子谱项值T_e.光谱分析表明C~1II_u态T_e=22968cm~(-1)是合适的.用~(39)K_2分子Morse势计算了(V′=0,J′=105)-(v″=1～10,J″=105)跃迁的Franck-Condon因子和跃迁强度,强度计算值和激光诱导荧光光谱测量值之间有令人满意的符合,进一步的r重心近似分析给出了~(39)K_2分子C~1II_u→X~1∑_g~+电偶极跃迁矩R_(?)随核间距r的归一化变化率为-0.157～-0.168 debye/(?)(4.22(?)相似文献   

The b1Sigma+(b0(+)) --> X3Sigma-(X10(+), X21) and a1Delta(a2) --> X21 Transitions of AsI

Emission spectra of the b1Sigma+(b0(+)) --> X3Sigma-(X10(+), X21) and a1Delta(a2) --> X21 transitions of AsI have been measured in the near-infrared spectral region with a Fourier-transform spectrometer. The arsenic iodide radicals were generated and excited in a fast-flow system by reaction of arsenic vapor (Asx) with iodine and microwave-discharged oxygen. The most prominent features in the spectrum are six band sequences of the strong b1Sigma+(b0(+)) --> X3Sigma-(X10(+)) transition in the range 800-900 nm. With much lower intensities the hitherto unknown b1Sigma+(b0(+)) --> X3Sigma-(X21) subsystem and the a1Delta(a2) --> X21 transition near 1660 nm are observed. Vibrational analyses have yielded improved molecular constants for the X10(+) and b0(+) states and first values of the electronic energies and vibrational constants of the X21 and a2 states (in cm-1), X21: Te = 289.8(2), omegae = 255.2(2), omegaexe = 0.68(7), a2: Te = 6305.4(3), omegae = 267.8(1), omegaexe = 0.56(2), where the numbers in parentheses are the standard deviations of the parameters. Copyright 1999 Academic Press.     

Supersymmetric benchmarks with non-universal scalar masses or gravitino dark matter

We motivate, propose and examine a new set of benchmark supersymmetric scenarios, some of which have non-universal Higgs scalar masses (NUHM) and others have gravitino dark matter (GDM). The scalar masses in these proposed models are either considerably larger or smaller than the narrow range allowed for the same gaugino mass m_1/2 in the constrained MSSM (CMSSM) with universal scalar masses m₀ and neutralino dark matter. Unlike the CMSSM, the proposed NUHM and GDM models with larger m₀ may have large branching ratios for Higgs and/or Z production in the cascade decays of heavier sparticles, whose detection we discuss. The novel phenomenology of the GDM models depends on the nature of the next-to-lightest supersymmetric particle (NLSP), which has a lifetime exceeding 10⁴ s in the proposed benchmark scenarios. In one GDM scenario the NLSP is the lightest neutralino χ, and the supersymmetric collider signatures are similar to those in previous CMSSM benchmarks, but with a distinctive spectrum that would be challenging for the LHC and ILC. In the other GDM scenarios based on minimal supergravity (mSUGRA), the NLSP is the lighter stau slepton , with a lifetime between ∼10⁴ and 3×10⁶ s. Every supersymmetric cascade would end in a , which would have a distinctive time-of-flight signature. Slow-moving ’s might be trapped in a collider detector or outside it, and the preferred detection strategy would depend on the lifetime. We discuss the extent to which these mSUGRA GDM scenarios could be distinguished from gauge-mediated models.     

First Observation of Hyperfine Structure in K(2)

The hyperfine structure of the (v'-v") = (27-0) band of the b(3)Pi(u0(+)) <-- X(1)Sigma(+)(g) transition has been observed by laser excitation spectroscopy in a highly collimated molecular beam. Hyperfine parameters for magnetic dipole and electric quadrupole interaction are derived from least-squares fitting of the hyperfine pattern and deperturbation between A(1)Sigma(+)(u) and b(3)Pi(u0(+)). Copyright 2000 Academic Press.     

A precise measurement of the B<Superscript> + </Superscript>, B<Superscript>0</Superscript> and mean b-hadron lifetime with the DELPHI detector at LEP I

Final results from the DELPHI Collaboration on the lifetime of B ⁺ and B⁰ mesons and the mean b-hadron lifetime, are presented using the data collected at the Z⁰ peak in 1994 and 1995. Elaborate, inclusive, secondary vertexing methods have been employed to ensure a b-hadron reconstruction with good efficiency. To separate samples of B ⁺ and B⁰ mesons, high performance neural network techniques are used that achieve very high purity signals. The results obtained are: and for the average b-hadron lifetime: Received: 6 October 2003, Revised: 12 December 2003, Published online: 25 February 2004     

The b1Sigma+(b0(+)) --> X3Sigma-(X10(+), X21) and a1Delta(a2) --> X21 Transitions of SbF, SbCl, SbBr, and SbI

Emission spectra of the a1Delta(a2) --> X21 and b1Sigma+(b0(+)) --> X3Sigma-(X10(+), X21) transitions of SbF, SbCl, SbBr, and SbI have been observed in the near-infrared spectral region. The antimony halide radicals were generated and excited in a fast-flow system by reaction of antimony vapor (Sbx) with the halides and microwave-discharged oxygen. The NIR chemiluminescence was measured with a Fourier-transform spectrometer equipped with Ge and InSb detectors. The spectra contain the known b1Sigma+(b0(+)) --> X3Sigma-(X10(+), X21) transitions in the range 730-910 nm and the hitherto unknown a1Delta(a2) --> X21 transitions in the range 1600-1900 nm. Vibrational analyses have yielded improved molecular constants for the X10(+), X21, and b0(+) states and the following constants of the a2 states (in cm-1): 121SbF: Te = 6815.6(5), omegae = 615.75(3), omegaexe = 2.62(1); 121Sb35Cl: Te = 6546.3(2), omegae = 379.8(1), omegaexe = 1.20(2); 121Sb79Br: Te = 6496.4(4), omegae = 265.9(2), omegaexe = 0.55(3); 121SbI: Te = 6366.7(3), omegae = 214.20(5), omegaexe = 0.430(9), where the numbers in parentheses are the standard deviations of the parameters. Copyright 1999 Academic Press.     

Improvement of the Spectroscopic Constants of the PF(A(3)Pi) State and Assignment of the PF(A-X) Transition Dipole Function

High-resolution laser-excitation spectra were acquired for the v'=3-7 levels of the PF(A(3)Pi(0,1,2)<--X(3)Sigma(-)) transition from PF(X(3)Sigma(-)) molecules generated in a discharge flow reactor. These results were combined with lower resolution excitation spectra for the v'=8-11 levels and with existing high-resolution data in the literature for v'=0 and 1 to assign improved spectroscopic constants for PF(A(3)Pi(0,1,2)). The abnormal vibrational energy level spacings for all spin components of the PF(A(3)Pi) state are evidence for a homogeneous interaction with another (3)Pi state. The Lambda-doublet separation in the PF((3)Pi(0)) substate increases with vibrational level, which is taken as evidence for interaction with the PF(b(1)Sigma(+)) state. Laser-induced fluorescence spectra from individual v'=0-5 levels were used to obtain vibrational band intensities of the A-X transition. The strong dependence of the transition dipole on the r-centroid is consistent with the reduction in the radiative lifetimes with increasing v' level. The similarity between the isovalent PF(A(3)Pi) and SO(A(3)Pi) states is noted and the bond dissociation energy of PF(X(3)Sigma(-)) is discussed. Copyright 2001 Academic Press.     

Biased diffusion and universality in model queues

We study the structure and robustness of universality classes for queueing, deriving analytic results for priority-based models with continuous-valued priorities. By mapping one model onto the problem of biased diffusion, we show that its distribution of waiting times, P(tau), decreases for large times tau as P(tau) approximately tau;{-3/2} or as P(tau) approximately tau;{-5/2}exp(-tau/tau_{0}) in different parameter regimes. In a second model, introducing a cost for switching between different classes of tasks substantially changes the asymptotic behavior of P(tau).     

Measurements of partial branching fractions for B-->Xulnu and determination of |Vub|

We present partial branching fractions for inclusive charmless semileptonic B decays B[over ]-->X_{u}lnu[over ], and the determination of the Cabibbo-Kobayashi-Maskawa matrix element |V_{ub}|. The analysis is based on a sample of 383 x 10;{6} Upsilon(4S) decays into BB[over ] pairs collected with the BABAR detector at the SLAC PEP-II e;{+}e;{-} storage rings. We select events using the invariant mass M_{X} of the hadronic system, the invariant mass squared, q;{2}, of the lepton and neutrino pair, the kinematic variable P+, or one of their combinations. We then determine partial branching fractions in limited regions of phase space: DeltaB=(1.18+/-0.09_{stat}+/-0.07_{syst}+/-0.01_{theor})x10;{-3} (M_{X}<1.55 GeV/c;{2}), DeltaB=(0.95+/-0.10_{stat}+/-0.08_{syst}+/-0.01_{theor})x10;{-3} (P+<0.66 GeV/c), and DeltaB=(0.81+/-0.08_{stat}+/-0.07_{syst}+/-0.02_{theor})x10;{-3} (M_{X}<1.7 GeV/c;{2}, q;{2}>8 GeV;{2}/c;{4}). Corresponding values of |V_{ub}| are extracted using several theoretical calculations.     

The splitting of low-lying states for hydroxyl molecule under spin--orbit coupling

The splitting of potential energy curves for the states $X^{2}\Pi _{3/2}$, $^{2}\Pi _{1/2}$ and $A^{2}\Sigma ^{ +}$ of hydroxyl OH under spin--orbit coupling (SOC) has been calculated by using the SO multi-configuration quasi-degenerate perturbation theory (SO-MCQDPT). Their Murrell--Sorbie (M--S) potential functions have been derived, then, the spectroscopic constants for $X^{2}\Pi _{3/2}$,$^{ 2}\Pi _{1/2}$ and $A^{2}\Sigma ^{ + }$ have been derived from the M--S function. The calculated dissociation energies for the three states are $D_{0}$[OH($X^{2}\Pi _{3/2})$]=34966.632cm$^{-1}$, $D_{0}$[OH($^{2}\Pi _{1/2})$]=34922.802cm$^{-1}$, and $D_{0}$[OH($A^{2}\Sigma ^{ + })$]=17469.794cm$^{-1}$, respectively. The vertical excitation energy $\nu [ {{ }^2\Pi _{1/2} ( {\nu = 0} ) \to {X}{ }^2\Pi _{3/2} ( {\nu = 0} )} ] = 139.6{\rm cm}^{-{\rm 1}}$. All the spectroscopic data for the $X^{2}\Pi _{3/2}$ and $^{2}\Pi _{1/2 }$ are given for the first time except the dissociation energy of $X^{2}\Pi _{3/2}$.