Hanle lifetime measurements of SrI 1P1 and CaI 1P1 levels excited by a neutral beam of 1 1S0 helium atoms

A 0.8 keV He(1 ¹S₀) beam was used to coherently excite the ¹P₁ levels of Sr and Ca targets. The coherence appears as an alignment of the excited state with respect to the beam axis. We report here the results of a Hanle measurement, or a zero-field level-crossing experiment, performed on these coherently excited levels. The radiative lifetimes of the SrI ¹P₁ and CaI ¹P₁ levels were measured to be 4.7 ns and 5.3 ns, respectively. These values are in good agreement with conventional Hanle measurements.     

Spectroscopy of the electron subbands on (1 1 1)-Si

We present measurements of infrared inter-subband absorption for electron subbands on (1 1 1)-Si for densities N_s up to ～ 10¹³ cm^?2 at 4.2 K for both parallel- and perpendicular-excitation geometries. Contrary to previously published work the depolarization shift is identified as a sizeable splitting of the resonance energies E^⊥₀₁ and E^z.dfnc;₀₁. The comparison with a recent calculations is given.     

Radiative lifetimes and tensor polarizabilities of 1s4f 1 F and 1s5f 1 F level of He I

He atoms have been excited by Ne⁺ ion impact and the depolarization of the fluorescence lines at 668 nm and 492 nm by magnetic and electric fields has been studied. The Ne⁺ ion energy could be chosen such that pure cascade level crossing signals were observed. From the widths of magnetic depolarization signals the radiative lifetimes τ(1s4f ¹ F)=74(2) ns and τ(1s5f ¹ F)=133(5) ns have been determined. By investigating the electric field splitting of the magnetic depolarization signals the tensor polarizabilities ¦α _ten(1s4f ¹ F)¦=0.58(1) kHz/(V/cm)² and ¦α _ten(1s5f ¹ F)¦=4.2(1) kHz/(V/cm)² have been deduced. From the latter value a mean frequencyv(1s5g?1s5f)=14.4 GHz of the transitions between the levels of the 1s5f configuration and those of the 1s5g configuration has been derived.α _ten(1s4f ¹ F) depends sensitively on the singlet-triplet mixing in the 1s4f configuration and thus a mixing coefficient could be deduced for this configuration.     

Levelcrossing experiments in the first excited1 P 1 states of the alkaline earths

The hyperfine structure of the lowest¹P₁ state of²⁵Mg,⁴³Ca,⁸⁷Sr,¹³⁵Ba and¹³⁷Ba have been measured by the level-crossing and anticrossing technique. The magnetic dipole and electric quadrupole coupling constants determined by these measurements are²⁵Mg(3s3p¹P₁):A=? 7.7(5) MHz; 16 MHz>B>0 MHz,⁴³Ca(4s4p¹P₁):A=? 15.3(4) MHz; ¦B¦<12 MHz,⁸⁷Sr (5s5p¹P₁:A=? 3.4(4) MHz;B=39(4) MHz,¹³⁵Ba(6s6p¹P₁):A=? 97.5(1.0) MHz;B=31(9)MHz,¹³⁷Ba(6s6p¹P₁):A=?109.2(1.2) MHz;B=51(12)MHz. The results have been compared with the predictions of the Breit-Wills theory of the two-electron hyperfine structure using the experimental data on the³P states. Large discrepancies have been observed which are due to different radial wave functions of thes andp electron in the triplet and singlet system. This effect has been taken into account by fitting the data with the aid of two additional parameters. That this procedure is justified is shown by an analysis of the fine structure splitting, the life times, and the isotopic shifts in thesp configurations of group II elements.     

Natural radiative lifetimes in the1 P 1 and1 F 3 sequences of Sr I

We have measured radiative lifetimes in the 5s n p ¹ P ₁ (n=5–29) and 5s n f ¹ F ₃ (n=4–11) Rydberg series in neutral strontium. The measurements were performed with single-step laser excitation starting from the ground state or from a metastable state populated by collisions. The decay photons were detected using delayed coincidence technique or a transient recorder. The presence of configuration interaction in the 5s n p ¹ P ₁ series can be observed aroundn=8. The perturbation in the 5s n f ¹ F ₃ series is not reflected in the behaviour of the lifetime values.     

Density functional study of hypophosphite adsorption on Ni (1 1 1) and Cu (1 1 1) surfaces

Surface structures and electronic properties of hypophosphite, H₂PO₂⁻, molecularly adsorbed on Ni(1 1 1) and Cu(1 1 1) surfaces are investigated in this work by density functional theory at B3LYP/6-31++g(d, p) level. We employ a four-metal-atom cluster as the simplified model for the surface and have fully optimized the geometry and orientation of H₂PO₂⁻ on the metal cluster. Six stable orientations have been discovered on both Ni (1 1 1) and Cu (1 1 1) surfaces. The most stable orientation of H₂PO₂⁻ was found to have its two oxygen atoms interact the surface with two PO bonds pointing downward. Results of the Mulliken population analysis showed that the back donation from 3d orbitals of the transition metal substrate to the unfilled 3d orbital of the phosphorus atom in H₂PO₂⁻ and 4s orbital's acceptance of electron donation from one lone pair of the oxygen atom in H₂PO₂⁻ play very important roles in the H₂PO₂⁻ adsorption on the transition metals. The averaged electron configuration of Ni in Ni₄ cluster is 4s^0.634p^0.023d^9.35 and that of Cu in Cu₄ cluster is 4s^1.004p^0.033d^9.97. Because of this subtle difference of electron configuration, the adsorption energy is larger on the Ni surface than on the Cu surface. The amount of charge transfers due to above two donations is larger from H₂PO₂⁻ to the Ni surface than to the Cu surface, leading to a more positively charged P atom in Ni_nH₂PO₂⁻ than in Cu_nH₂PO₂⁻. These results indicate that the phosphorus atom in Ni_nH₂PO₂⁻ complex is easier to be attacked by a nucleophile such as OH⁻ and subsequent oxidation of H₂PO₂⁻ can take place more favorably on Ni substrate than on Cu substrate.     

1H NMR Studies of 1-Ethylimidazole Binding to Cytochrome C

Abstract

Kinetic and equilibrium data for 1-EtIm binding to cyt c at temperature range of 303–319K have been determined at pH 7.0 by using ¹HNMR method. Thermodynamic values (ΔH°=39.5 kJ mol^?1, ΔS° = 154 J mol^?1K^?1 and Ea = 142 kJ mol^?1) are obtained from Van't Hoff and Arrhenius's relations. Some hyperfine shifted resonances of l-EtIm cyt c have been assigned for the first time using 1D saturation transfer experiments. The origin of the asymmetric spin density distribution in heme groups of 1-EtIm cyt c and the reason of low affinity of cytochrome c for 1-EtIm are also discussed move toward upfield from original position. However, Te-2, 4 substituents in cyt c are more electron withdrawing than the propionic acid side chains, which lead to the 5-methyl group going toward downfield.     

Stark effect investigations of the 4f 14 6s 6p 3 P 1 and1 P 1 levels of ytterbium

The tensor polarizabilities of the 4f ¹⁴ 6s 6p ³ P ₁ level were investigated for all stable Ytterbium isotopes by the method of optical double resonance. The tensor polarizabilities were deduced from the rf-resonance signals in parallel electric and magnetic fields. The value obtained for the even Yb isotopes is in good agreement with the results derived from the measurements on the odd isotopes. The mean value isα _ten(³ P ₁)0=5.99(34)kHz/(kV/cm)². The tensor polarizability of the 4f ¹⁴ 6s 6p ¹ P ₁ level of¹⁷¹Yb was measured by means of the level crossing technique with parallel electric and magnetic fields. The experimental result isα _ten(¹ P ₁)=?14.3(1.4)kHz/(kV/cm)². This is compared with the prediction of the LS coupling approximation using the experimental data of the³ P ₁ level. Only poor agreement is obtained which is due to the configuration mixing in the¹P₁ level.     

The A 1Σ+ → X 1Σ+ bands of the isotopic lithium hydrides

In order to obtain a better understanding of the X¹Σ⁺ ground state and the A¹Σ⁺ state potential energy curves of lithium hydride and to examine in detail the concept of “mass-reduced quantum numbers” for both an ordinary (X¹Σ⁺) and an anomalous (A¹Σ⁺) electronic state, the emission spectra of the A¹Σ⁺ → X¹Σ⁺ bands of the isotopic lithium hydrides and deuterides were photographed in the 3000–5000-Å region with a 3.4-m Ebert Spectrograph. The bands found involved v″ = 0 to 7 to various v′ = 0 to 17 for ⁶LiH, and v″ = 0 to 7 to various v′ = 1 to 16 for ⁶LiD. Additional bands involving v″ = 4 and 5 were also found for ⁷LiH. The vibrational-rotational spectroscopic analysis of ⁷LiH, ⁶LiH, and ⁶LiD are reported here, as are the reanalyses of the ⁷LiH and ⁷LiD data reported by Crawford and Jorgensen. New Rydberg-Klein-Rees (RKR) A¹Σ⁺ and X¹Σ⁺ potential curves have been constructed for each individual molecule and are reported, but detailed isotopic comparisons will be reported in subsequent publications.     

JF1/B6F1 Ngly1−/− mouse as an isogenic animal model of NGLY1 deficiency

N-Glycanase 1 (NGLY1) deficiency is a congenital disorder caused by mutations in the NGLY1 gene. Because systemic Ngly1^−/− mice with a C57BL/6 (B6) background are embryonically lethal, studies on the mechanism of NGLY1 deficiency using mice have been problematic. In this study, B6-Ngly1^−/+ mice were crossed with Japanese wild mice-originated Japanese fancy mouse 1 (JF1) mice to produce viable F₂ Ngly1^−/− mice from (JF1×B6)F₁ Ngly1^−/+ mice. Systemic Ngly1^−/− mice with a JF1 mouse background were also embryonically lethal. Hybrid F1 Ngly1^−/− (JF1/B6F1) mice, however, showed developmental delay and motor dysfunction, similar to that in human patients. JF1/B6F1 Ngly1^−/− mice showed increased levels of plasma and urinary aspartylglycosamine, a potential biomarker for NGLY1 deficiency. JF1/B6F1 Ngly1^−/− mice are a useful isogenic animal model for the preclinical testing of therapeutic options and understanding the precise pathogenic mechanisms responsible for NGLY1 deficiency.     

Infrared spectra of CS2: Measurement of “hot” bands associated with the 2325 cm−1 and 2962 cm−1 bands

The 12⁰1-00⁰0 and 02⁰1-00⁰0 transitions of CS₂ have been measured with a resolution of 0.025 cm^?1. The following “hot” bands associated with these transitions were also measured 13¹1?01¹0, 22⁰1? 10⁰0, 14⁰1?02⁰0, 14²1?02²0, 03¹1?01¹0, 12⁰1?10⁰0, 04⁰1?02⁰0, 04²1?02²0, 13¹1?11¹0, and 22⁰1?20⁰0. Improved rotational constants are given for the ground state and the first bending state. A consistent set of band constants is given for all the above vibrational transitions.     

Hyperfine structure of the 4s4p1P1-state of67Zn by level crossing spectroscopy

The magnetic dipole coupling constantA of the 4s 4p¹P₁ state of⁶⁷Zn was measured in a level crossing experiment. The result is A(4s4p¹P₁ ⁶⁷Zn)= 17.7(5) MHz. In a modified Breit-Wills theory thisA factor leads to a parameter λ_P= 0.71(3), which describes the difference in the radial wave functions of thep-electron in 4s4p¹P₁ and³P₁ states respectively. The lifetime of the 4s4p¹P₁ state was remeasured by Hanle-effect experiments. The result τ=1.41± 0.04 nsec is in good agreement with other measurements.     

Microwave spectra of eight isotopic modifications of 1-chloro-1-fluoroethylene

The rotational spectra of eight isotopomers of 1-chloro-1-fluoroethylene in the 6-22 GHz region have been collected and analyzed. Each rotational transition is split into hyperfine components by the chlorine (either ³⁵Cl or ³⁷Cl) nuclear quadrupole coupling interaction and additionally, one or more smaller interactions such as the spin-rotation interaction due to the fluorine atom, hydrogen-hydrogen spin-spin coupling interactions, and in appropriately substituted species, the deuterium nuclear quadrupole hyperfine interaction. The rotational constants derived from these isotopomers allow the determination of average and Kraitchman substitution structures for 1-chloro-1-fluoroethylene, whereas the availability of the diagonal chlorine nuclear quadrupole coupling constants for all the isotopomers provides complete quadrupole coupling tensors for both ³⁵Cl and ³⁷Cl. In the course of this work, the rotational spectrum of an excited vibrational state of the normal isotopomer was observed, which ab initio calculations suggest should be assigned to ν₉=1, an in-plane bending motion at the CFCl end of the molecule.     

Determination of the B1Π-X1Σ and C1Σ-X1Σ electronic transitions strengths of CaO

The strengths S_e of the B¹Π-X¹∑ and C¹∑-X¹∑ electronic transitions of the CaO molecule have been determined by absorption measurements in a shock tube. Powdered calcium oxide and a gaseous mixture of oxygen and argon in the ratio of 1:5 or 1:9 were introduced into the shock channel. The CaO gas-phase concentration was determined by using the equilibrium constant for CaO?Ca+O; atomic oxygen concentration was calculated and that of calcium was measured spectroscopically. The values of S_e (in atomic units) are for B¹Π-X¹∑, 2.32±0.49; for C¹∑-X¹∑, 2.88±0.67.     

Lifetimes of the levels 31P, 41P and 51P in Li II by the beam-foil technique

Radiative lifetimes of the Li II levels 3¹P, 4¹P and 5¹P are extracted from the observed vacuum-UV-transitions 3¹P → 2¹S, 4¹P → 2¹S, and 5¹P → 2¹S, respectively. The measured values agree well with theory.     

The C1 IIg-A1 IIu Emission Spectrum of 12C13C

A few bands of the C¹II_g -A¹II_u system of ¹²C¹³C molecule have been photographed and five of them have been rotationally analyzed. Molecular constants for v = 0, 1 and 2 in the C¹ II_g and in A¹II_u states have been obtained using a nonlinear least-squares procedure in which all analyzed bands were fitted simultaneosly.     

Some perturbation calculations for 1s2p, 1s 22p,and 1s 22s

The Dalgarno interchange theorem is used, together with the U function approach, to evaluate the first order perturbation corrections to <r ₁ ^-1+r ₂ ^-1> and <r ₁ + r ₂> for the two-electron states 1s2p ¹ P and 1s2p ³ P. The results for <r ₁ + r ₂> are extended by using a screening approximation, and are compared with the results of accurate variational calculations. The first order perturbation correction to spin-weighted expectation values of type <ΣV(r_j )s_zj > is given for the three-electron states 1s ²2p ² P and 1s ²2s ² S. The case V(r_j ) = r _j ^-1 is treated in detail.     

Two-photon photoemission from Ni (1 1 0) and (1 1 1) surfaces

Photoemission was observed when the samples were irradiated with photons in the energy range from 2.5 to 3.3 eV from a tunable dye laser with an intensity of 10⁸Wcm^?2. The emission shows a quadratic intensity dependence. The variation with angle of incidence and polarization is different for the two surfaces. The result obtained from the (1 1 0) surface is discussed with help of the band structure as a two-photon surface photoelectric effect.