Note: Improved line strengths of rovibrational and rotational transitions within the X3Σ− ground state of NH

Recently, a line list including positions and transition strengths was published for the NH X3Σ− rovibrational and rotational transitions. The calculation of the transition strengths requires a conversion of transition matrix elements from Hund’s case (b) to (a). The method of this conversion has recently been improved during other work on the OH X2Π rovibrational transitions, by removing an approximation that was present previously. The adjusted method has been applied to the NH line list, resulting in more accurate transition strengths. An updated line list is presented that contains all possible transitions with v′ and v″ up to 6, and J up to between 25 and 44, depending on the band

Line Strengths of Rovibrational and Rotational Transitions in the X2Π^2\Pi Ground State of OH

A new line list including positions and absolute intensities (in the form of Einstein $A$ values and oscillator strengths) has been produced for the OH ground X\DP\ state rovibrational (Meinel system) and pure rotational transitions. All possible transitions are included with v\primed and v\Dprimed up to 13, and $J$ up to between 9.5 and 59.5, depending on the band. An updated fit to determine molecular constants has been performed, which includes some new rotational data and a simultaneous fitting of all molecular constants. The absolute line intensities are based on a new dipole moment function, which is a combination of two high level ab initio calculations. The calculations show good agreement with an experimental v=1 lifetime, experimental $\mu_\mathrm{v}$ values, and $\Delta$v=2 line intensity ratios from an observed spectrum. To achieve this good agreement, an alteration in the method of converting matrix elements from Hund's case (b) to (a) was made. Partitions sums have been calculated using the new energy levels, for the temperature range 5-6000 K, which extends the previously available (in HITRAN) 70-3000 K range. The resulting absolute intensities have been used to calculate O abundances in the Sun, Arcturus, and two red giants in the Galactic open and globular clusters M67 and M71. Literature data based mainly on [O I] lines are available for the Sun and Arcturus, and excellent agreement is found.Comment: 17 pages, 8 figues. 7 supplementary files: dipole moment functions (OH-X-DMFs.txt), equilibrium constants (OH-X-Equilibrium_Constants.txt), partition function (OH-X-Q_5-6000K.dat), PGOPHER file with molecular constants and transition matric elements (OH-XX.pgo), vibrational Einstein A and f values (OH-XX-Avv_fvv.txt), line list (OH-XX-Line_list.txt), and OH-Transformation_Equation_Extra.doc

Automatic assignment and fitting of spectra with PGOPHER

An open source program for automatically assigning complex, well resolved spectra.</p

Measurement of the orientation of buffer-gas-cooled, electrostatically-guided ammonia molecules

AbstractThe extent to which the spatial orientation of internally and translationally cold ammonia molecules can be controlled as molecules pass out of a quadrupole guide and through different electric field regions is examined. Ammonia molecules are collisionally cooled in a buffer gas cell, and are subsequently guided by a three-bend electrostatic quadrupole into a detection chamber. The orientation of ammonia molecules is probed using (2+1) resonance-enhanced multiphoton ionisation (REMPI), with the laser polarisation axis aligned both parallel and perpendicular to the time-of-flight axis. Even with the presence of a near-zero field region, the ammonia REMPI spectra indicate some retention of orientation. Monte Carlo simulations propagating the time-dependent Schrödinger equation in a full basis set including the hyperfine interaction enable the orientation of ammonia molecules to be calculated – with respect to both the local field direction and a space-fixed axis – as the molecules pass through different electric field regions. The simulations indicate that the orientation of ∼95% of ammonia molecules in JK=11 could be achieved with the application of a small bias voltage (17V) to the mesh separating the quadrupole and detection regions. Following the recent combination of the buffer gas cell and quadrupole guide apparatus with a linear Paul ion trap, this result could enable one to examine the influence of molecular orientation on ion-molecule reaction dynamics and kinetics

Einstein A Coefficients and Oscillator Strengths for the A 2Π-X2Σ+ (Red) and B 2Σ+-X2Σ+ (Violet) Systems and Rovibrational Transitions in the X2Σ+ State of CN

Line strengths have been calculated in the form of Einstein A coefficients and f-values for a large number of bands of the A 2Π-X 2Σ+ and B 2Σ+-X 2Σ+ systems and rovibrational transitions within the X 2Σ+ state of CN using Western\u27s PGOPHER program. The J dependence of the transition dipole moment matrix elements (the Herman-Wallis effect) has been taken into account. Rydberg-Klein-Rees potential energy functions for the A 2Π, B 2Σ+ , and X 2Σ+ states were computed using spectroscopic constants from the A 2Π-X 2Σ+ and B 2Σ+-X 2Σ+ transitions. New electronic transition dipole moment functions for these systems and a dipole moment function for the X 2Σ+ state were generated from high level ab initio calculations and have been used in Le Roy\u27s LEVEL program to produce transition dipole moment matrix elements (including their J dependence) for a large number of vibrational bands. The program PGOPHER was used to calculate Einstein A coefficients, and a line list was generated containing the observed and calculated wavenumbers, Einstein A coefficients and f-values for 290 bands of the A 2Π-X 2Σ + transition with v′ = 0-22, v″ = 0-15, 250 bands of the B 2Σ+-X 2Σ+ transition with v′ = 0-15, v″ = 0-15 and 120 bands of the rovibrational transitions within the X 2Σ+ state with v = 0-15. The Einstein A coefficients have been used to compute radiative lifetimes of several vibrational levels of the A 2Π and B 2Σ + states and the values compared with those available from previous experimental and theoretical studies. © 2014. The American Astronomical Society

First high-resolution infrared spectra of 2–13C-propane:Analyses of the ν26 (B2) c-type and ν9 (A1) b-type bands

International audienc

セッション 21セイキ ノ ニッチュウ カンケイ ニ ツイテ

日中台共同研究「現代中国と東アジアの新環境」 ②21世紀の日中関係 : 青年研究者の思索と対