A spectroscopic case for SPSi detection: The third-row in a single molecule

Abstract

In moving beyond the second row of the periodic table for molecules of astronomical and atmospheric significance, the exploration of sulfur and phosphorus chemistry is essential. Additionally, silicon is abundant in most astrophysical environments and is a major component of most rocky bodies. The triatomic molecule composed of each of these atoms is therefore a tantalizing candidate for spectroscopic characterization for astrophysical reasons as well as gaining further understanding into the chemical physics of molecules that are not carbon-based. The current work employs high-level quantum chemical techniques to provide new insights into this simplest of heterogeneous third-row atom systems. The fundamental vibrational frequencies are all within the 350-600 cm range and do not demonstrate strong anharmonicities. These frequencies, rotational constants, vibrationally excited state spectroscopic data, and related isotopic substitution information produced will aid in laboratory experimentation and, even potentially, telescopic observation since modern instruments possess the power to resolve extremely fine details.

On the Detectability of the HSS, HSO, and HOS Radicals in the Interstellar Medium

“…The previous CcCRE discrete variable representation (DVR) results utilizing a similar PES to that constructed in this work, but a different method for solving the Watson Hamiltonian, are in excellent agreement with those values computed here as has been shown previously for SPSi (Finney et al 2016). The quartic distortion constants are also nearly identical for both HSS and DSS as a prime example of the correlation between the two theoretical approaches.…”

“…CCSD(T)/aug-cc-pV5Z dipole moment computations from the equilibrium geometry are also undertaken, and double-harmonic intensities from MP2/6-31 +G * within the Gaussian09 program (Mller & Plesset 1934;Hehre et al 1972;Frisch et al 2009) produce the fundamental vibrational intensities. Such intensities are known to corroborate well with CCSD(T)/aug-cc-pVTZ intensities (Yu et al 2015;Finney et al 2016). …”

“…Utilizing restricted-openshell Hartree-Fock reference wavefunctions Lauderdale et al 1991;Watts et al 1993) for CCSD(T), the geometry is computed with the aug-cc-pV5Z basis set (Dunning 1989; Kendall et al 1992) with the necessary, additional tight d functions for sulfur (Wilson & Dunning 2004) as well as the Martin-Taylor (MT) core correlating basis set (Martin & Taylor 1994) inclusive and exclusive of core electrons correlated. The difference in the MT bond lengths and bond angle are added to the CCSD(T)/aug-cc-pV5Z geometry as has been done for many related systems (Fortenberry et al 2014b;Fortenberry & Francisco 2015a, 2015bFortenberry & Lukemire 2015;Fortenberry & Thackston 2015;Finney et al 2016;Kitchens & Fortenberry 2016).…”

“…It is necessary to life as we know it, gives rise to novel chemistry in extreme environments like hot springs and black smokers on Earth, heavily influences the atmospheric chemistry of Venus (Krasnopolsky 2007(Krasnopolsky , 2012 as well as the surface chemistry of Io, and is present in various terrestrial pollutants (Tchir & Spratley 1975;Hawkins & Downs 1984). Consequently, sulfur cannot be neglected for astrochemical analysis, and an understanding for its importance in the chemistry of space has been continually growing since various molecular sulfur detections began in the 1970s (Morris et al 1975;Henkel et al 1983;Johansson et al 1984;Ziurys et al 1984;Cernicharo et al 1987Cernicharo et al , 2000Kaifu et al 1987;Saito et al 1987;Turner 1987Turner , 1992Kahane et al 1988;Martín-Pintado et al 1992;Boyle et al 1994;Turner et al 1998;Schilke et al 2001Schilke et al , 2003Mauersberger et al 2004;Sakai et al 2007;Finney et al 2016).…”

ArCH2+: A Detectable Noble Gas Molecule

“…All electronic structure computations employ the MOLPRO 2015.1 quantum chemistry program save for the MP2/6‐31+G(d) double‐harmonic vibrational intensities and dipole moment as well as the MP2/aug‐cc‐pVDZ transition state geometry optimization which are undertaken with Gaussian09 . Such intensities are known to compare well with higher‐level computations and even experiment . The transition state geometry is then used to compute a CCSD(T)/aug‐cc‐pVTZ single point energy estimate of the reaction barrier.…”