Tunable XUV radiation generated by nonresonant frequency tripling in neon

Nonresonant frequency tripling of ultraviolet (UV) radiation (λ_uv = 216–223 nm, generated by sum frequency mixing of the outputs of a frequency doubled pulsed dye laser and of the Nd-YAG pump laser) generates in neon coherent light in the extreme ultraviolet (XUV). The XUV radiation is tunable in spectral regions of negative dispersion λ_xuv = 72.05- 73.58 nm and λ_xuv = 74.3–74.36 nm at the high energy side of the transitions $\text{2p-3s′[}\text{built1}\text{2}\text{, 1]}$ and $\text{2p-3s[}\text{built3}\text{2}\text{, 1]}$. At UV input powers of 0.1-0.3 MW the generated XUV power was typically P_xuv = 0.1-0.4 W (1.5–6 x 10⁸ photons/pulse). Since present UV dye laser systems provide at λ_uv pulse powers of almost 1 MW the XUV output could easily be increased by more than one order of magnitude.     

Self-induced generation of an off-axis frequency shifted radiation from atoms

The transient resonant linear response at wavelength λ_a of an N two-level atom vapor driven by a strong pulse with wavelength λ_f = λ_a - |Δλ| is shown to promote an emission of radiation peaked at wavelength λ_c = λ_a + |Δλ| in a conical shell around the propagation axis of the incident beam. In the limit of weak excitation, i.e. for an incident Rabi frequency much smaller than the detuning, the cone angle is found to be equal to 2λμ(2N/ch|Δλ|)^{$\text{1}\text{2}$} where μ is the transition dipole moment.     

Pionic X-rays from 12, 13C

The energies and widths of pionic 2p-1s and 3d-2p X-rays have been measured in ^12,13C. Values obtained are

${}^{12}\text{C: 2p-1s E=93.221(55)}\text{keV}\text{, τ=2077(14)}\text{keV}$

$\text{3d-2p E=18.400(6)}\text{keV}\text{, τ=1.17(11)}\text{eV}$

${}^{13}\text{C: 2p-1s E=92.227(27)}\text{keV}\text{, τ=2.59(11)}\text{keV}$

$\text{3d-2p E=18.427(5)}\text{keV}\text{, τ=0.97(10)}\text{eV}$

The muonic 2p-1s X-ray energies in ^12,13C have also been measured. The strong interaction effects are discussed in relation to recent low-energy pion scattering measurements.     

A frequency-doubled frequency-stabilized cw ring dye laser for spectroscopy: A study of the λ = 293.3 nm transition in In1

In this letter a frequency-doubled frequency-stabilized CW ring dye laser for the wavelength region 292–305 nm is described. 500 μW U.V. power combined with a 2 MHz linewidth and a 7 GHz scanwidth has been obtained by intracavity frequency doubling in an ADA crystal. The set-up has been tested on the hyperfinestructure of the λ = 293.3 nm transition 5p²P_{$\text{3}\text{2}$} → 7s²S_{$\text{1}\text{2}$} in In1.     

A spectrum of rhenium oxide

The arc emission spectrum of the ReO molecule has been photographed in the region 590–860 nm and three bands of a single electronic transition have been rotationally analyzed. The separation of lines of the isotopic molecules ¹⁸⁵ReO and ¹⁸⁷ReO leads to the conclusion that the vibrational assignments for these bands are 1-0, 0-0, and 0–1. It is conceivable that an electronic isotope shift of ～0.08 cm^?1 exists. The following vibrational and rotational data (cm^?1) have been determined: ν₀(0-0) = 14 038.42, $\text{Δ}\text{G′(}\text{1}\text{2}\text{) = 867.85}$, $\text{Δ}\text{G″(}\text{1}\text{2}\text{) = 979.14}$; B′_e = 0.3889, α′_e = 0.0019, B″_e = 0.4257, α″_e = 0.0043. It is concluded that Λ′ ? Λ″ = +1 with Λ″ ≥ 2.     

Series expansions for a generalized XY hamiltonian: II. Tricritical behaviour of the Takagi model

The high-temperature series expansions for the square of the fluctuation in the order parameter, for the specific heat, the concentration and the concentration susceptibility for the Takagi model on an f.c.c. lattice are analysed in the field variables. We obtain for the critical exponent $\text{γ =}\text{4}\text{3}$ and the specific heat is possibly logarithmically divergent. If we take the tricritical point to be determined by γ_t = 1, the tricritical exponents α_t, λ_t and ω_t are found to be consistent with $\text{1}\text{2}$.     

An attempt of molecular design and synthesis of 3,4′/4,3′‐disubstituted benzylideneanilines with specified UV–Vis absorption maximum wavelength

Thirty‐one samples of 3,4′/4,3′‐disubstituted benzylideneanilines (XBAY) with specified UV–Vis absorption maximum wavelength (λ_max) were designed and synthesized by applying the equation (Eqn 1 ) which was abstracted from the UV–Vis absorption maximum wavelength energy (ν_max = 1/λ_max) of 4,4′‐disubstituted benzylideneanilines. Then, the UV–Vis data (λ_max) of the designed compounds were measured in anhydrous ethanol. The predicted UV–Vis data of designed compounds are in agreement with the experimental ones, in which the mean absolute error is 2.9 nm. The results show that Eqn 1 is applicative for the prediction of UV–Vis absorption λ_max values of both 4,4′‐disubstituted benzylideneanilines and 3,4′/4,3′‐disubstituted benzylideneanilines. For a same pair of groups (X and Y), one can at least get four disubstituted benzylideneaniline compounds which have different λ_max values. It perhaps provides a convenient method to design an optical material for benzylideneaniline compounds. Copyright © 2014 John Wiley & Sons, Ltd.     

The 404.5-nm system of the ReO molecule

Observations on the emission spectrum of ReO in the region 375–870 nm are reported. Five bands of a $\text{ΔΩ}\text{= 0}$ system with (0, 0) band at 404.5 nm have been rotationally analyzed and the principal results for ¹⁸⁷ReO are (in cm^?1) ν₀ = 24 709.90, B′_e = 0.3819, B″_e = 0.4252, ω′_e = 874.8₂, and $\text{Δ}\text{G″(}\text{1}\text{2}\text{) = 979.1}{}_2$. Data on the minor isotopic species ¹⁸⁵ReO are also reported. It is suggested that broad rotational profiles found in bands near 842 nm may be due to nuclear hyperfine structure.     

A high pressure 585.3 nm neon hydrogen laser

Lasing was observed on the 3p′ ($\text{1}\text{2}$)₀?3s′($\text{1}\text{2}$)⁰₁ (i.e. 2p₁?1s₂ in the Paschen notation) Ne transition at λ = 585.3 nm in mixtures of Ne and H₂. A small (200 mm active length), Blumlein type, transverse-discharge driven assembly delivered laser pulses with fwhm between 30 and 140 ns at pressures of up to 700 mbar. The population inversion is ascribed to a fast Penning reaction between H₂ and Ne which effectively depopulates the lower laser level.     

Liouville field theory coupled to a critical Ising model: non-perturbative analysis,duality and applications

Two different kinds of interactions between a $\text{Z}{}_{\mathrm{n}}$-parafermionic and a Liouville field theory are considered. For generic values of n, the effective central charges describing the UV behavior of both models are calculated in the Neveu–Schwarz sector. For n=2 exact vacuum expectation values of primary fields of the Liouville field theory, as well as the first descendent fields are proposed. For n=1, known results for sinh-Gordon and Bullough–Dodd models are recovered whereas for n=2, exact results for these two integrable coupled Ising–Liouville models are shown to exchange under a weak–strong coupling duality relation. In particular, exact relations between the parameters in the actions and the mass of the particles are obtained. At specific imaginary values of the coupling and n=2, we use previous results to obtain exact information about: (a) integrable coupled models like Ising–$\text{M}{}_{\mathrm{p/p\prime }}$, homogeneous sine-Gordon model SU(3)₂ or the Ising–XY model, (b) Neveu–Schwarz sector of the Φ₁₃ integrable perturbation of N=1 supersymmetric minimal models. Several non-perturbative checks are done, which support the exact results.     

Generation of narrowband tunable VUV radiation at the Lyman-α wavelength

Tunable narrowband VUV radiation has been generated at the Lyman-α wavelength $\text{λ =}\text{1216}\text{\&}\text{A}\text{ring}$; by frequency tripling in krypton the frequency-doubled output of a powerful dye laser system which is excited with the second harmonic of a Nd-YAG laser. 5 ns long UV dye laser pulses ($\text{λ =}\text{3646}\text{A}\text{?}$) of 1.8 MW peak power yielded VUV light pulses of 2.2 W (5.4 × 19⁹ photons/pulse). The bandwidth of the dye laser radiation could be narrowed to 8.7 × 10^-3cm^-1 (4.6 × 10^-3 Å). The expected bandwidth of the VUV is less than 5.2 × 10^-2cm^-1 (7 × 10^-4 Å). The tunable VUV radiation is used for the recording of the absorption spectra of the Lyman-α resonance transitions in atomic hydrogen and deuterium with doppler-limited resolution.     

The visible and photographic infrared spectrum of osmium oxide

The emission spectrum of OsO has been photographed in the region 405–875 nm where many new bands have been observed. In favorable cases the ${}^{190}\text{OsO}{}^{192}\text{OsO}$ isotopic splittings have been resolved and aid in vibrational assignments. Three visible bands in the region 433–470 nm have been assigned as (1,0), (0,0), and (0,1) of a $\text{ΔΩ}\text{= 0}$ electronic transition. The (0,0) and (0,1) bands have been rotationally analyzed, yielding principal constants (cm^?1) for the visible system of ν₀ = 22 273.3, B′₀ = 0.3657, D′₀ = 2.8 × 10^?7, B″_e = 0.4023, D″_e = 3.2 × 10^?7, $\text{Δ}\text{G″(}\text{1}\text{2}\text{) = 780.7}$, and $\text{Δ}\text{G″(}\text{1}\text{2}\text{) = 884.9}$. A band at 825.4 nm has been found to be a $\text{ΔΩ}\text{= +1}$ (0,0) band with the same lower state as in the analyzed visible bands. Constants for the upper state of the ir system are ν₀ = 12 109.7, B′₀ = 0.3845, and D′₀ = 3.1 × 10^?7 cm^?1.     

Anhydrous cuprous chloride: The paramagnetic phase

Anhydrous cuprous chloride is monoclinic, space group: C 2/m. We can consider it as being a layered compound consisting of pseudohexagonal layers in the (001) plane. Nevertheless, the symmetry deviation and the uncommon position of the pseudohexagonal environment symmetry axis do not lead to a unaxial anisotropy, contrary to the case of CuF₂ · 2H₂O. If we compare the experimental results with the isotropic quadratic 2d planar Heisenberg model with spin $\text{1}\text{2}$ (lines [1], we find $\text{J}\text{k}\text{= 37}\text{K}$, with J the antiferromagnetic exchange integral.     

Hole centers in γ-irradiated,oxidized Al2O3

ESR observations of centers with $\text{S =}\text{1}\text{2}\text{, g ? 2, S = 1, g ? 2}$ have been made at 77 K on oxidized Al₂O₃ after γ-irradiation at 30°C. From the radiation growth data, it is shown that the $\text{S =}\text{1}\text{2}$ centers are precursors of the S = 1 centers. In addition, when the S = 1 centers anneal out at about 110°C, the $\text{S =}\text{1}\text{2}$ centers reappear and eventually anneal out at about 260°C. Previously Gamble and Cox, respectively, observed $\text{S =}\text{1}\text{2}$ and S = 1 paramagnetic centers in electron-irradiated nominally pure Al₂O₃ and γ-irradiated, oxidized, titanium-doped Al₂O₃. The models proposed for these centers were one hole and two holes trapped on oxygen ions adjacent to Al³⁺ vacancies. Our results further substantiate these models.     

Analysis of the 2770-Å emission system in I2

A weak emission spectrum of I₂ near 2770 Å is reanalyzed and found to to minate on the A(1u³Π) state. The assigned bands span v″ levels 5–19 and v′ levels 0–8. The new assignment is corroborated by isotope shifts, band profile simulations, and Franck-Condon calculations. The excited state is an ion-pair state, probably the 1g state which tends toward $\text{I}{}^{\mathrm{?}}\text{(}{}^1\text{S) +}\text{I}{}^{\mathrm{+}}\text{(}{}^3\text{P}{}_1\text{)}$. In combination with other results for the A state, the analysis yields the following spectroscopic constants: T″_e = 10 907 cm^?1, $\text{D}$″_e = 1640 cm^?1, ω″_e = 95 cm^?1, $\text{R″}{}_{\mathrm{e}}\text{= 3.06}\text{A}\text{?}$; T′_e = 47 559.1 cm^?1, ω′_e = 106.60 cm^?1, $\text{R′}{}_{\mathrm{e}}\text{= 3.53}\text{A}\text{?}$.     

Rotational analyses and vibrational assignments of the 463- and 474-nm bands of NO2

The excitation spectrum of NO₂ was investigated in the blue region by using a Nd:YAG laser-pumped dye laser. The 463- and 474-nm bands of the ²B₂-²A₁ system were identified and analyzed using the simplification that occurs if the excitation spectrum is monitored at particular wavelengths. Band origins and rotational constants were obtained. Vibrational assignments have been given to these bands by comparing the Franck-Condon Factors calculated for the ²B₂-²A₁ system with the fluorescence intensities of bands going to different vibrational levels of the ground state. The vibrational assignments and molecular constants obtained in this work are (v′₁, v′₂, v′₃) = (3, 11, 0)ν₀(K′ = 0) = 21584.1, $\text{B}\text{= 0.405}$, and $\text{∥}\text{?}\text{′∥ = 0.05}\text{cm}{}^{\mathrm{?1}}$ for the 463-nm band; and (v′₁, v′₂, v′₃) = (2, 12, 0), ν₀(K′ = 1) = 21104.9, $\text{B}\text{= 0.408}$, and $\text{∥}\text{?}\text{′∥ = 0.03}\text{cm}{}^{\mathrm{?1}}$ for the 474-nm band.     

Microwave spectral study of 2-fluorophenol: cis conformer

The microwave spectra of 2-fluorophenol and its deuterated species have been observed and analyzed in the frequency ranges 12.5–18.0 GHz (KU band) and 21.5–26.0 GHz (K band) in the ground vibrational state at room temperature. For the normal species, the radio frequency-microwave double resonance spectrum has been recorded in the frequency range 30.0–38.0 GHz. Three rotational and five quartic centrifugal distortion constants for the normal species, $\text{A}\text{?}\text{= 3337.86 ± 0.02}$, $\text{B}\text{?}\text{= 2231.92 ± 0.01}$, $\text{C}\text{?}\text{= 1337.52 ± 0.01}$, d_J = (3.5 ± 2.9) × 10^?4, d_JK = (?4.9 ± 1.5) × 10^?3, d_K = (?3.2 ± 1.0) × 10^?3, d_WJ = (?2.0 ± 1.0) × 10^?7, d_WK = (2.6 ± 0.8) × 10^?6 (in MHz), and three rotational constants for the deuterated species, $\text{A}\text{?}\text{= 3324.70 ± 0.03}$, $\text{B}\text{?}\text{= 2177.95 ± 0.03}$, $\text{C}\text{?}\text{= 1315.96 ± 0.03}$ (in MHz), have been obtained. Consideration of the r_s coordinate of the hydroxyl hydrogen atom leads to the assignment of the spectra to the cis conformer of the molecule. An r₀ structure for the cis conformer has been proposed. The nonbonded OH ? F distance is lower by about 0.3 Å than the sum of the van der Waals radii.     

The Ã1A″ ← X̃1A′ electronic transition in formyl chloride,CHClO

The ultraviolet absorption spectrum of formyl chloride has been recorded under conditions of modest resolution, 0.75 nm/mm, and long pathlengths, 96 m. The 314- to 269-nm spectrum proved to have well-defined vibrational fine structure and was assigned to the electron promotion, $\text{n → π}{}^1$. A comparison of the spectra of CHClO at 25 and ?78°C with CDClO led to the assignments: pseudo-origin, ν₂, ν₄, ν₅, and ν₆; $\text{32754.7}\text{32775.3}$, $\text{1153.8}\text{1092.0}$, $\text{633.6}\text{633.4}$, $\text{306.3}\text{303.1}$, and $\text{779.5}\text{566.5}\text{cm}{}^{\mathrm{?1}}$ for $\text{CHClO}\text{CDClO}$, respectively. A fit of the 6⁰, 6², 6³, and 6⁵ levels to those generated from a Gaussian-quadratic model potential yielded a barrier height of 1608.8 cm^?1 and an out-of-plane angle of 48.6° for the $\text{A}\text{?}$ state.     

Autler-Townes effect in double optical resonance

Two frequency stabilized dye lasers and a sodium atomic beam are used to study the Autler-Townes effect in the aligned 3S_{$\text{1}\text{2}$}, F = 2, $\text{M}{}_{\mathrm{F}}\text{= 2 → 3P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$, F = 3, M_F = 3, → 4D_{$\text{5}\text{2}$}, F = 4, M_F = 4 states. This system is to a very good approximation an isolated three-level atom. The Autler-Townes doublet splittings are measured as a function of the intensities of the two lasers and their detunings from resonance. The experimental results are in good agreement with theory.     

A gauge theory of weak and electromagnetic interactions with spontaneous parity breaking

We present a unified gauge theory of weak and electromagnetic interactions in which parity is spontaneously broken together with gauge invariance, by the Higgs mechanism. The gauge group is SU(2) × U(1), and a heavy neutrino is associated with every charged lepton. After the breaking of the original parity-conserving theory, both a purely vector electromagnetic current and the usual V-A charged currents are obtained. Z is coupled to a vector electron current, and the model predicts equal $\text{ν}{}_{\mathrm{\mu }}\text{e}\text{and}\text{ν}{}_{\mathrm{\mu }}\text{e}$ cross sections. Extension to hadrons is made by introducing three charmed quarks p′, n′ and λ′ of the same charges as p, n and λ. All the experimental results $\text{(ν}{}_{\mathrm{\mu }}\text{e}\text{,}\text{ν}{}_{\mathrm{\mu }}\text{e}\text{,}\text{ν}{}_{\mathrm{<mtext>e</mtext>}}\text{e}$, ν_μ and $\text{ν}{}_{\mathrm{\mu }}$ hadron scatterings) are compatible with a value of sin²θ_W of order 0.4.