OBSERVATION OF SOME Ω = 1/2 ELECTRONIC STATES OF NICKEL DEUTERIDE, NiD, WITH LASER-INDUCED FLUORESCENCE

\begin{wrapfigure}{l}{0pt} \includegraphics[scale=0.16]{GraphAbs.eps} \end{wrapfigure} The five lowest-lying electronic states of nickel hydride (NiH) are usually labeled $^2\Delta_{5/2}$, $^2\Pi_{3/2}$, $^2\Delta_{3/2}$, $^2\Sigma^+_{1/2}$ and $^2\Pi_{1/2}$, although there is significant mixing between them. These states arise from the $d^9$ electron configuration of Ni$^+$, perturbed by an H$^-$ ligand. A variety of vibrational levels has been observed in each, and the aggregate data set has been well modelled as a `supermultiplet' by the Field group\footnote{J. A. Gray, M. Li, T. Nelis and R. W. Field, J. Chem. Phys. \textbf{95}, 7164 (1991)}. For the deuterated isotopologue NiD, only the $^2\Delta_{5/2}$, $^2\Pi_{3/2}$ and $^2\Delta_{3/2}$ states have been reported in the literature. A multi-isotope supermutiplet fitting including both the NiH and (more limited) NiD data\footnote{M. Abbasi, A. Shayesteh, P. Crozet and A. J. Ross, J. Mol. Spectrosc. \textbf{349}, 49 (2018)} provided predictions for the two $\Omega=1/2$ states of the NiD supermultiplet. Experimental observation was needed to validate (and improve) the model. We report on laser-induced fluorescence experiments conducted both at the University of New Brunswick and at Universit\'e Lyon 1 in which the $^2\Sigma^+_{1/2}, v=0,1,2$ and $^2\Pi_{1/2},v=0,1$ levels of NiD were identified and rotationally analyzed. The existing multi-isotope supermultiplet model proved remarkably accurate in predicting the energy and structure of these $\Omega=1/2$ states. In addition, a higher-lying $\Omega=1/2$ electronic state [16.7]0.5 has been identified in NiD, with no obvious analogue in NiH. The [16.7]0.5-$^2\Sigma^+_{1/2}$ and [16.7]0.5-$^2\Pi_{1/2}$ transitions proved to be a rich source of information about the two lower states

Observing quantum monodromy: an energy-momentum map built from experimentally-determined level energies obtained from the ⱱ7 far-infrared band system of ncncs

The concept of Quantum Monodromy (QM) provides a fresh insight into the structure of rovibrational levels in those flexible molecules for which a bending mode can carry the molecule through the linear configuration. To confirm the existence of QM in a molecule required the fruits of several strands of development: the formulation of the abstract mathematical concept of monodromy, including the exploration of its relevance to systems described by classical mechanics and its manifestation in quantum molecular applicationsthe development of the required spectroscopic technology and computer-aided assignmentand the development of a theoretical model to apply in fitting to the observed data. We present a timeline for each of these strands, converging in our initial confirmation of QM in NCNCS from pure rotational data alone.\footnote{B. P. Winnewisser \emph{et al.}, Phys. Rev. Lett. \textbf{95}, 243002 (2005).} In that work a Generalised SemiRigid Bender (GSRB) Hamiltonian was fitted to the experimental rotational structure. Rovibrational energies calculated from the fitted GSRB parameters allowed us to construct an ``Energy-Momentum" map and confirm the presence of QM in NCNCS. In further experimental work at the Canadian Light Source Synchrotron we have identified a network of transitions directly connecting the relevant energy levels and thereby have produced a refined Energy Momentum map for NCNCS from experimental measurements alone. This map extends from the ground vibrational level to well above the potential energy barrier, beautifully illustrating the characteristic signature of QM in a system uncomplicated by interaction with other vibrational modes

Observations of the low-lying Ω = 1/2 states of nickel deuteride, NiD

International audienc

LASER EXCITATION SPECTROSCOPY OF 58^{58}NiH IN A MAGNETIC FIELD

Author Institution: LASIM, Universite Lyon 1 \& CNRS, 43 Bd du 11 novembre 1918, F-69622 Villeurbanne, France; Department of Physics and Center for Laser, Atomic, and Molecular Sciences, University of New Brunswick, Fredericton, Canada E3B 5A3Recent laboratory measurements of isotopologue $^{58}$NiH by laser excitation around 17000$-$18000 cm$^{-1}$ in a magnetic field have allowed us to study several electronic systems of this molecule. Zeeman patterns were analysed using literature values for ground state Lande factors (1997) 4179}. Effective electronic Lande factors g_{\emph{eff}} have been determined. They show strong variation with parity in the rotational levels in some $\Omega'$=3/2 states, giving evidence for extensive mixing between excited electronic states. \newline %\begin{table}[h] % \scriptsize \begin{center} \begin{tabular}{|c|c|c|c|c|} \multicolumn{5}{c}{Effective electronic Lande factors g_{\emph{eff}}} \\ \multicolumn{5}{c}{}\\ \hline &\multicolumn{2}{|c|}{$E(\Omega=3/2),v=1$} & \multicolumn{2}{|c|}{$I(\Omega=3/2),v=0$}\\ \hline $J$ & $e$ & $f$ & $e$ & $f$ \\ \hline 1.5 & 1.058 & 1.142 & 1.640 & 1.638 \\ 2.5 & 0.992 & 1.365 & 1.937 & 1.895 \\ 3.5 & 0.844 & 1.737 & 2.371 & 2.294 \\ 4.5 & 0.587 & 2.238 & 2.870 & 2.734 \\ 5.5 & 0.415 & 2.933 & 3.552 & 3.328 \\ 6.5 & 0.233 & 3.671 & 4.326 & 4.110 \\ \hline \end{tabular} \end{center} % aption{Effective electronic Lande factors $g_{eff}$} %\end{table

The spectrum of N₂ from 4,500 to 15,700 cm⁻¹ revisited with PGOPHER

International audienceUsing a reference molecular atlas to ensure self-consistency of wavelength calibration is widespread practice. Boesch & Reiners (Astronomy & Astrophysics 582 A43 (2015)) reported a line list from a discharge of molecular nitrogen from 4500 to 11000 cm −1 for this purpose. With a hollow-cathode discharge source, we have extended the experimental spectrum up to 15700 cm −1 , to include the range of Ti:sapphire lasers, since the density of N 2 lines is greater than atomic atlases in common use. Recognizing that experimental conditions can vary, we have also analysed the spectra (comprising several B ³Π g-A ³Σ u + , B' ³Σ u −-B ³Π g , and W ³Δ u-B ³Π g N 2 bands) with standard Hamiltonians, so that any part of the discharge spectrum 4500-15700 cm −1 can be simulated. Parameters are given to do this with the spectral simulation and analysis package PGOPHER. (C. Western, J. Quant. Spectrosc. Rad. Transf., 186, 221 (2016)). The analysis also included high-level ab initio calculations of potential energy curves, transition moments and spin-orbit coupling constants and these were used in preparing the model, extending the potential range of applicability. The results are available in a variety of formats to suit possible applications, including the experimental spectrum in ASCII, a detailed line list with positions and Einstein A coefficients, and a PGOPHER input file to synthesize the spectrum at selectable temperature and resolution.

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

Spectroscopy Of Ncncs At The Canadian Light Source: The Far-infrared Spectrum Of The Ν7 Region From 60-140 Cm−1

We report on the analysis of our spectrum from 60-140 \wn\ of the $\nu_7$ bending fundamental and associated hot band sequence of NCNCS, obtained on the far-infrared beamline at the Canadian Light Source synchrotron. The data were collected in May 2013, building upon what we learned conducting experiments in May 2011 and 2012 on this molecule. Calculations indicated that the $\nu_7$ system was very weak (one of the four weakest fundamental bands, all of comparable strength), but its spectrum became evident when 30 mTorr of NCNCS was admitted into the 2-m-long sample cell, through which the synchrotron beam passed 40 times. The best spectrum so far has been obtained with 121 mTorr of gas. Loomis-Wood plots reveal many branches, some of which were unambiguously assignable to $\Delta \nu_7 = +1$ subbands for $\nu_7^{\prime\prime} = 0, 1, 2, 3$ and for $K_a = 0, 1,2$ with $\Delta K_a = 0$ (a-type subbands) by comparison of lower-state combination differences with those obtained from the published pure-rotational data. We will continue the analysis by assigning as many a-type subbands as possible and by searching for b-type subbands with $\Delta K_a = \pm 1$ so that the connections between $K_a$-stacks can be measured. Finally, we will simultaneously fit the infrared and rotational data with a generalized semi-rigid bender Hamiltonian

Spectroscopy of the X1Σ+, a1π and B1Σ+ electronic states of mgs

The spectra of some astrophysical sources contain signatures from molecules containing magnesium or sulphur atoms. Therefore, we have extended previous studies of the diatomic molecule \chem{MgS}, which is a possible candidate for astrophysical detection. Microwave spectra of X$^1\Sigma^+$ , the ground electronic state, were reported in 1989\footnote{S. Takano, S. Yamamoto and S. Saito, Chem. Phys. Lett. \textbf{159}, 563-566 (1989).} and 1997\footnote{K. A. Walker and M. C. L. Gerry, J. Mol. Spectrosc \textbf{182}, 178-183 (1997).}, and the B$^1\Sigma^+$--X$^1\Sigma^+$ electronic absorption spectrum in the blue was last studied in 1970\footnote{M. Marcano and R. F. Barrow, Trans. Faraday Soc. \textbf{66}, 2936-2938 (1970).}. We have investigated the B$^1\Sigma^+$--X$^1\Sigma^+$ 0-0 spectrum of \chem{MgS} at high resolution under jet-cooled conditions in a laser-ablation molecular source, and have obtained laser-induced fluorescence spectra from four isotopologues. Dispersed fluorescence from this source identified the low-lying A$^1\Pi$ state near 4520 \wn. We also created \chem{MgS} in a Broida oven, with the help of a stream of activated nitrogen, and took rotationally resolved dispersed fluorescence spectra of the B$^1\Sigma^+$--A$^1\Pi$ transition with a grating spectrometer by laser excitation of individual rotational levels of the B$^1\Sigma^+$ state via the B$^1\Sigma^+$--X$^1\Sigma^+$ transition. These spectra provide a first observation and analysis of the A$^1\Pi$ state

Observation of the 4f\u21923d\u3c3 transition of the ArH molecule

The emission spectrum of ArH contains a band near 10 110 cm\u20131 that appears to be the analogue of the 3d \u2013 4p, v = 0 \u2013 0, band of ArD, observed and analysed near 10 230 cm\u20131. However, previous attempts to assign the rotational structure of this band of ArH were unsuccessful. Here we observe and analyse the 4f \u2013 3d band of ArH near 4400 cm\u20131, and are then able to calculate the rotational structure of the 3d \u2013 4p transition entirely from known data. The observed band is similar but not identical to the calculated band. We speculate that the observed spectrum is a v \u2013 v sequence band of 3d \u2013 4p, where the v 0 upper state is populated through some mechanism peculiar to this isotopomer.Le spectre d'\ue9mission de ArH contient une bande pr\ue8s de 10 110 cm\u20131 qui semble \ueatre l'analogue de la bande 3d \u2013 4p, v = 0 \u2013 0 de ArD observ\ue9e pr\ue8s de 10 230 cm\u20131. Les tentatives pr\ue9c\ue9dentes pour identifier la nature rotationnelle de cette bande ont \ue9chou\ue9. Ici, nous \ue9tudions la bande 4f \u2013 3d de ArH pr\ue8s de 4400 cm\u20131 et sommes alors capables de calculer la structure rotationnelle de la transition 3d \u2013 4p \ue0 partir de donn\ue9es connues. La bande observ\ue9e est similaire \ue0 celle calcul\ue9e, mais pas identique. Nous sp\ue9culons que le spectre observ\ue9 est une s\ue9quence v \u2013 v de 3d \u2013 4p o\uf9 l'\ue9tat sup\ue9rieur v 0 est peupl\ue9 via un m\ue9canisme particulier \ue0 cet isotopom\ue8re.NRC publication: Ye