Measurements of vibrational transitions in small molecules can be used to test for a possible time variation of the electron-proton mass ratio.J.-P. Uzan. Rev. Mod. Phys. 75, 403–455 (2003).n our experiments, our goal is to measure two-photon v = 2 ← v = 0 vibrational transitions in the hydroxyl (OH) radical near 2 ×3500 cm⁻¹ with a relative accuracy of 10⁻¹⁴. Reaching this level of accuracy requires a mid-infrared laser with a linewidth of much less than 1 kHz, as well as the ability to compare the frequency of this laser with an absolute frequency standard. To achieve the high short-term stability necessary for such a narrow linewidth, we are implementing a 532-nm CW reference laser by locking a frequency-doubled Nd:YAG laser to a molecular iodine transition using saturated absorption spectroscopy. Similar setups have demonstrated relative stabilities of around 10⁻¹⁴ at the one-second timescale.Döringshoff, K., Mohle, K., Nagel, M., Kovalchuk, E. V., Peters, A: High performance iodine frequency reference for tests of the LISA laser system. EFTF-2010 24th European Frequency and Time Forum (2010).he stability of this reference laser will then be transfered onto the idler of a 1064-nm-pumped optical parametric oscillator (OPO) using an optical frequency comb as a transfer oscillator. The frequency comb will also be used to measure the absolute optical frequencies of the various lasers and compare them to a GPS-linked radio frequency reference, providing long-term stability and absolute accuracy for the spectroscopic measurements.

---

Footnotes:

J.-P. Uzan. Rev. Mod. Phys. 75, 403–455 (2003).I Döringshoff, K., Mohle, K., Nagel, M., Kovalchuk, E. V., Peters, A: High performance iodine frequency reference for tests of the LISA laser system. EFTF-2010 24th European Frequency and Time Forum (2010).T

The tokamak wall protection is one of the prime concerns, and for this purpose, limiters are used. Graphite is commonly used as a limiter material and first wall material for complete coverage of the internal vacuum vessel surfaces of the tokamak. From the past few years, we are working to identify and quantify the impurities deposited on the different part of Aditya Tokamak in collaboration with the Scientists at Institute of Plasma Research, Ahmedabad, India using Laser Induced Breakdown Spectroscopy (LIBS) [1-3]. Laser induced breakdown spectroscopy (LIBS) spectra of limiter of Aditya Tokamak have been recorded in the spectral range of 200-900 nm in open atmosphere. Along with atomic and ionic spectral lines of the constituent elements of the limiter (1-3), LIBS spectra also give the molecular bands. When a high power laser beam is focused on the sample, laser induced plasma is produced on its surface. In early stage of the plasma Back ground continuum is dominated due to free-free or free-bound emission. Just after few nanoseconds the light from the plasma is dominated by ionic emission. Atomic emission spectra is dominated from the laser induced plasma during the first few microsecond after an ablation pulse where as molecular spectra is generated later when the plasma further cools down. For this purpose the LIBS spectra has been recorded with varying gate delay and gate width. The spectra of the limiter show the presence of molecular bands of CN and C2. To get better signal to background ratios of the molecular bands, different experimental parameters like gate delay, gate width, collection angle and collection point (spatial analysis off the plasama) of the plasma have been optimized. Thus the present paper deals with the variation of spectral intensity of the molecular bands with different experimental parameters. Keywords: Limiter, Molecular bands, C2, CN. References: 1. Proof-of-concept experiment for On-line LIBS Analysis of Impurity Layer Deposited on ptical Window and Other Plasma Facing Components of Aditya Tokamak G. S. Maurya, R. Kumar, A. Kumar and A. K. Rai, Review of Scientific Instruments (In Press) 2. Analysis of deposited impurity material on the surface of optical window of the Tokamak using LIBS, (2014) G. S. Maurya, A. Jyotsana, R. Kumar, A. Kumar and A. K. Rai, Physica Scripta 89, 075601 3. Spatial analysis of impurities on the surface of flange and optical window of the Tokamak using Laser Induced Breakdown Spectroscopy, G. S. Maurya, A. Jyotsana, A. Kumar and A. K. Rai,(2014), Optics and Lasers in Engineering, 56, 13–18

The hydrogen molecule as the most abundant neutral molecule in the universe is an important object of studies in different areas of science, especially astrophysics. The precision spectroscopy of the hydrogen molecule is particularly useful to verify the quantum electrodynamics theory (QED) in a molecular system. The electric quadrupole transitions of the second overtone of H₂ have been recorded with a high precision cavity ring-down spectrometer.Tan Y, Wang J, Cheng C-F, Zhao X-Q, Liu A-W, Hu S-M, J Mol Spectrosc 2014;300:60–4; total of eight lines including the extremely weak S₃(5) line in the 784−852 nm range have been observed. The line positions have been determined to an accuracy of 3 ×10⁻⁴ cm⁻¹ and the line intensities were determined with a relative accuracy of about 1%. The deviations between the experimental and theoretical frequencies are less than 5 ×10⁻⁴ cm⁻¹, which is much smaller than the claimed theoretical uncertainty of 0.0025cm⁻¹. The data from this experiment along with other high-quality H₂ spectra have also been analyzed by the Hartmann-TranTran H, Ngo NH, Hartmann J-M, J Quant Spectrosc Radiat Transf 2013;129:199–203;rofile as a test case for incorporatingWcislo P, Gordon IE, Tran H, Tan Y, Hu S-M, Campargue A, et al., Accepted J Quant Spectrosc Radiat Transf HighRus Special Issue, 2015arametrization of this profile in the HITRANRothman LS, Gordon IE, Babikov Y, Barbe A, Chris Benner D, Bernath PF, et al., J Quant Spectrosc Radiat Transf 2013;130:4–50;atabase. It was incorporated in the new relational structure of the HITRAN database (www.hitran.org) and into the HITRAN Application Programming Interface (HAPI)Kochanov RV, Gordon IE, Rothman LS, Wcislo P, Hill C, Wilzewski JS, Submitted to J Quant Spectrosc Radiat Transf HighRus Special Issue, 2015.or the case of H₂ spectra.

---

Footnotes:

Tan Y, Wang J, Cheng C-F, Zhao X-Q, Liu A-W, Hu S-M, J Mol Spectrosc 2014;300:60–4;A Tran H, Ngo NH, Hartmann J-M, J Quant Spectrosc Radiat Transf 2013;129:199–203;p Wcislo P, Gordon IE, Tran H, Tan Y, Hu S-M, Campargue A, et al., Accepted J Quant Spectrosc Radiat Transf HighRus Special Issue, 2015p Rothman LS, Gordon IE, Babikov Y, Barbe A, Chris Benner D, Bernath PF, et al., J Quant Spectrosc Radiat Transf 2013;130:4–50;d Kochanov RV, Gordon IE, Rothman LS, Wcislo P, Hill C, Wilzewski JS, Submitted to J Quant Spectrosc Radiat Transf HighRus Special Issue, 2015.f

Study of lead halide perovskites is a burgeoning field of research owing to their applications in solar cells and myriads of other light harvesting and emitting devices. In this work we have employed Terahertz time domain spectroscopy (THz-TDS) and time-resolved THz spectroscopy (TRTS) to study dielectric properties and carrier dynamics occurring within CsPbBr₃ perovskite nanocrystals (NCs) in presence of electron and hole acceptor molecules. The THz-TDS spectrum of CsPbBr₃ NCs features a strong and broad band with a peak around 3.4 THz which originates from multiple IR-active optical phonon modes of the nature of Pb-Br stretching and Br-Pb-Br bending vibrations. We observed very efficient electron and/or hole transfer in presence of either an electron or a hole acceptor, or both. Also, in presence of either an electron or hole acceptor the diffusion length reduces to half (4.1 μm) in comparison to parent NCs (9.2 μm). In presence of both, electron and hole acceptor molecules the diffusion length reduces to 0.6 μm. Considerable decrease in mobility values is also observed for the NCs in presence of electron and hole acceptor molecules. Details of the study will be discussed in the talk.

ThF⁺ has been chosen to replace HfF⁺ for a second-generation measurement of the electric dipole moment of the electron (eEDM). Compared to the currently running HfF⁺ eEDM experiment, ThF⁺ has several advantages: (i) the eEDM-sensitive state (³∆₁) is the ground state, which facilitates a long coherence time [1]; (ii) its effective electric field (35 GV/cm) is 50% larger than that of HfF⁺, which promises a direct increase of the eEDM sensitivity [2]; and (iii) the ionization energy of neutral ThF is lower than its dissociation energy, which introduces greater flexibility in rotational state-selective photoionization via core-nonpenetrating Rydberg states [3]. In this talk, we first present our strategy of preparing and utilizing core-nonpenetrating Rydberg states for rotational state-selective ionization. Then, we report spectroscopic data of laser-induced fluorescence of neutral ThF, which provides critical information for multi-photon ionization spectroscopy. [1] D. N. Gresh, K. C. Cossel, Y. Zhou, J. Ye, E. A. Cornell, Journal of Molecular Spectroscopy, 319 (2016), 1-9 [2] M. Denis, M. S. Nørby, H. J. A. Jensen, A. S. P. Gomes, M. K. Nayak, S. Knecht, T. Fleig, New Journal of Physics, 17 (2015) 043005. [3] Z. J. Jakubek, R. W. Field, Journal of Molecular Spectroscopy 205 (2001) 197–220.

We report high resolution spectroscopic results for 1,2-dithiine-(1,2-dithia-3,5-cyclohexadiene,C₄H₄S₂) in the Gigahertz and Terahertz spectroscopic ranges and exploratory theoretical calculations of parity violation and tunneling processes in view of a possible experimental determination of the parity violating energy difference ∆_pvE in this chiral molecule.M. Quack , Fundamental Symmetries and Symmetry Violations from High-resolution Spectroscopy, Handbook of High Resolution Spectroscopy, M. Quack and F. Merkt eds.,John Wiley & Sons Ltd, Chichester, New York, 2001, vol. 1, ch. 18, pp. 659-722.^,S. Albert, I. Bolotova, Z. Chen, C. Fábri, L. Horný, M. Quack, G. Seyfang and D. Zindel,Proceedings of the 20th Symposium on Atomic, Cluster and Surface Physics (SASP 2016), Innsbruck University Press, 2016, pp. 127−130, ISBN:978−3−903122−04−8. and to be publishedheory predicts that the parity violating energy difference in the ground state (

pv

E

≅ 11x10−11(hc) cm−1)is in principle measurable as it is much larger than the calculated tunneling splitting for the symmetrical potential ∆

_

E

10^-24(hc) cm⁻¹. With a planar transition state for stereomutation at about 2500 cm⁻¹tunneling splittings become appreciable above 2300 cm⁻¹. This makes levels of well defined parity accessible to parity selection by available powerful infrared lasers and thus useful for one of the existing experimental approaches towards molecular parity violation.P. Dietiker, E. Miloglyadov, M. Quack, A. Schneider and G. Seyfang, J. Chem. Phys. 143,244305 (2015).he new GHz spectra lead to greatly improved ground state rotational parameters for 1,2−dithiine. These are used as starting point for the first successful analyses of high resolution interferometric Fourier Transform Infrared (FTIR, THz) spectra for the fundamentals

17 (1308.873 cm−1or 39.23903 THz), ν

_22 (623.094 cm⁻¹or 18.67989 THz) and

3 (1544.900 cm−1or 46.314937 THz) for which highly accurate spectroscopic parameters are reported. The results are discussed in relation to current efforts to measure ∆

_pv

In recent years, `damping functions', which characterize the weakening of inverse-power-sum long-range interatomic interaction energies with increasing electron overlap, have become an increasing important component of models for diatomic molecule interaction potentials.R.J. Le Roy, C. C. Haugen, J. Tao and Hui Li, Mol. Phys. 109,435 (2011).owever, a key feature of models for damping functions, their portability, has received little scrutiny. The present work set out to examine all available ab initio induction and dispersion damping function dataP.J. Knowles and W.J. Meath,J. Mol. Phys. 60, 1143 (1987); R.J. Wheatley and W.J. Meath,J. Mol. Phys. 80, 25 (1993); R.J. Wheatley and W.J. Meath J. Chem. Phys. 179, 341 (1994); R.J. Wheatley and W.J. Meath,J. Chem. Phys. 203, 209 (1996).nd to attempt to devise a `global' scheme for diatomic molecule damping functions. It appears that while neutral (H, He, Li, and Ne, homonuclear and mixed) and anion (H⁻ with H, He and Li) species obey (approximately) one common rule, proton plus neutral (H⁺ with H, He and Li) and non-proton-cation plus neutral systems (He⁺ and Li⁺ with H, He and Li), must each be treated separately. However, for all three cases, a version of the Douketis-Scoles-ThakkarC. Douketis,G. Scoles, S. Marchetti, M. Zen and A. J. Thakkar, J. Chem. Phys. 76, 3057 (1982).ionization potential)^power factor is a key scaling parameter.

---

Footnotes:

R.J. Le Roy, C. C. Haugen, J. Tao and Hui Li, Mol. Phys. 109,435 (2011).H P.J. Knowles and W.J. Meath,J. Mol. Phys. 60, 1143 (1987); R.J. Wheatley and W.J. Meath,J. Mol. Phys. 80, 25 (1993); R.J. Wheatley and W.J. Meath J. Chem. Phys. 179, 341 (1994); R.J. Wheatley and W.J. Meath,J. Chem. Phys. 203, 209 (1996).a C. Douketis,G. Scoles, S. Marchetti, M. Zen and A. J. Thakkar, J. Chem. Phys. 76, 3057 (1982).(

The goal of this research is to obtain an optimal, portable, global description of, and summary of the dynamical properties of, the A ³Π₁ and X ¹Σ⁺ states of I^35/37Cl, by using `direct potential fits' (DPFs) to all of the available spectroscopic data for this system to determine optimal analytic potential energy functions for these two states that represent all of those data (on average), within the experimental uncertainties. The DPF method compares observed spectroscopic data with synthetic data generated by solving the radial Schrödinger equation for the upper and lower level of every observed transition for some parameterized analytic potential function(s), and using least-squares fits to the data to optimize those parameters. The present work uses the Morse/Long-Range (MLR) potential function form because it is very flexible, can incorporate the correct theoretically known inverse-power-sum long-range behaviour, is everywhere continuous and differentiable to all orders, and has robust extrapolation properties at both large and small distances. The DPF approach also tends to require fewer fitting parameters than do traditional Dunham analyses, as well as having much more robust extrapolation properties in both the v and J domains. The present work combines the data for the A ³Π₁ and X ¹Σ⁺ states obtained in 1980 by Coxon et al. J.A. Coxon, R.M. Gordon and M.A. Wickramaaratchi, J. Mol. Spectrosc. 79 (1980) 363 and 380.sing UV and near-infrared grating spectrometers, with our measurements in the 0.7-0.8μm region, obtained using a CW Ti:Sapphire Ring Laser. T.Yukiya, N. Nishimiya and M. Suzuki, J. Mol. Spectrosc. 269 (2011) 193. The results of this study and our new fully analytic potential energy functions for the A ³Π₁ and X ¹Σ⁺ states of ICl will be presented.

---

Footnotes:

 J.A. Coxon, R.M. Gordon and M.A. Wickramaaratchi, J. Mol. Spectrosc. 79 (1980) 363 and 380.u  T.Yukiya, N. Nishimiya and M. Suzuki, J. Mol. Spectrosc. 269 (2011) 193.