Laboratory Measurements and Astronomical Search of the HSO Radical

Transcription

1 Laboratory Measurements and Astronomical Search of the HSO Radical Valerio Lattanzi Garching (Germany) June 21, 2016

2 Authors Cristina Puzzarini & Gabriele Cazzoli (Dip. Chimica Giacomo Ciamician Università di Bologna) Jürgen Gauss & Till Kirsch (Institut für Physikalische Chemie, Universität Mainz) José Cernicharo & Belén Tercero (Grupo de Astrofísica Molecular, ICMM CSIC)

3 Motivations Many sulfur (single S) species detected in the interstellar gas From diatomic up to CH 3 CH 2 SH Wide variety of astronomical environments, including extragalactic

4 Motivations Many sulfur (single S) species detected in the interstellar gas From diatomic up to CH 3 CH 2 SH Wide variety of astronomical environments, including extragalactic Sulfur chemistry in space still puzzling no depletion in diffuse medium much lower abundance in dense, cold clouds Sulfur on grains? when? how? which form? no H2 S in grains OCS and SO 2 (?)

5 Motivations Many sulfur (single S) species detected in the interstellar gas From diatomic up to CH 3 CH 2 SH Wide variety of astronomical environments, including extragalactic Sulfur chemistry in space still puzzling no depletion in diffuse medium much lower abundance in dense, cold clouds Sulfur on grains? when? how? which form? no H2 S in grains OCS and SO 2 (?) Location and chemical form of missing sulfur

6 Motivations Large abundance of triatomic S, O, and H species Especially in high mass star-forming regions Key intermediates in the atmospheric oxidation of H 2 S to H 2 SO 4 Prominent role in catalytic cycles of stratospheric ozone depletion First experimental evidence of HSO by Schurath et al. (1977) low-resolution chemiluminescence visible spectra High-resolution spectroscopy by Endo et al. (1981) HSO and DSO hydrogen hyperfine coupling constant

7 HSO Experiment A electronic ground state (Endo et al. 1981) µ a = 2.20 D (Webster et al. 1982)

8 HSO Experiment Measured in the 194 GHz 1.2 THz range Free space cell, 3m long, single pass arrangement Cryogenic InSb and Schottky diode detectors Room temperature measurements Sulfur is very sticky! Similar results with two settings: 1. DC discharge ( ma) of H 2 S and O 2 (1:2) total pressure < 20 mtorr 2. DC discharge ( ma) of 40 mtorr of H 2 O cleaner experiment

9 HSO Experiment G. Cazzoli et al.: Laboratory measurements and astro Fig. 1. N = 10 6,4(5) 9 6,3(4) transition at GHz. In black, the signal Fig. 2. N obtained

10 HSO Experiment rements and Confirmation astronomical search by means for theof HSO magnetic radical field

11 Computations H = H rot + H S N + H hfs All computations made with CFOUR A e, B e, and C e at the CBS+CV+fT+fQ level Vibrational corrections at the CCSD(T)/cc-pCVQZ level Quartic and sextic at the CCSD(T)/cc-pCVQZ level Electronic and nuclear Spin-Rotation at the CCSD(T)/cc-pCV5Z level Isotropic and anisotropic hyperfine coupling constants at the aug-cc-pcv5z level

12 Results Rotational Constants Parameter This work Previous Experiment Theory A 0 (MHz) (12) (14) B 0 (MHz) (10) (83) C 0 (MHz) (10) (83) D N (khz) (13) (11) D NK (khz) (11) (40) D K (MHz) 26.24(11) [27.2] d 1 (khz) (43) (65) d 2 (khz) (30) (52) H N (mhz) (75) H NK (Hz ) 2.779(88) 2.28 H KN (Hz ) 144.7(43) H K (khz) [6.43] 6.43 h (mhz) [-8.32] h 2 (mhz) [3.69] 3.69 h 3 (mhz) 1.10(22) L JK (mhz) -11.4(32)

13 Results Spin rotation and Hyperfine interactions Parameter This work Previous Experiment Theory ɛ aa (MHz) (10) ( ) (16) ɛ bb (MHz) (17) (-438.9) (31) ɛ cc (MHz) 0.191(21) 2.82(3.29) 0.210(48) ɛ ab (MHz) (16) 404.8(403.3) (80) ɛ NK aa e (MHz) 0.047(12) ɛ K aa e (MHz) 2.979(10) 3.023(35) ɛ NK bb e (MHz) (32) ɛ K bb e (MHz) (36) ɛ NK cc e (khz) (30) a F (H) (MHz) (50) (-34.58) (42) T aa(h) (MHz) (86) (-13.25) (71) T bb (H) (MHz) 10.45(14) 10.71(11.25) 10.41(11) T ab (H) (MHz) [-7.53] f -7.56(-7.53) [-7.8] f C aa(h) (khz) (-21.56) C bb (H) (khz) 2.51(2.51) C cc(h) (khz) -1.52(-1.59)

14 Astronomical observations Source Coordinates [J2000.0] HPBW [ ] Frequencies [GHz] Orion KL α=5 h 35 m 14 ṣ 5 (IRAM 30m) δ= Orion KL α=05 h 35 m 14 ṣ 5 (ALMA SV) δ= Hot core Orion KL α=05 h 35 m 14 ṣ 1 (ALMA SV) δ= Compact ridge Orion KL α=05 h 35 m 14 ṣ 2 (ALMA SV) δ= MM (IRAM 30m) α=17 h 47 m 20 ṣ Sgr B2(N) Cold gas δ= (GBT 100m) α=17 h 47 m 19 ṣ 8 δ= Sgr B2(N) α=17 h 47 m 20 ṣ 0 (IRAM 30m) δ= Hot gas B1-b α=03 h 33 m 20 ṣ 0 (IRAM 30m) δ=

15 Astronomical observations Source v LSR v FWHM d sou T rot N(HSO) (km s 1 ) (km s 1 ) ( ) (K) (cm 2 ) Orion KL (IRAM 30m) (2.0±0.6) Orion KL (ALMA SV) Hot core Orion KL (4±1) (ALMA SV) Compact ridge (1.0±0.3) Orion KL (1.0±0.3) (ALMA SV) (1.0±0.3) MM4 Sgr B2(N) (1.0±0.3) Cold gas (1.0±0.3) Sgr B2(N) (700±200) (IRAM 30m) (100±30) Hot gas (100±30) B1-b (IRAM 30m) (0.010±0.003)

16 (a) Notes. Hot core component (dsou = 10 HSO Astronomical 00, vfwhm = 10 km s Spectra 1 ) column densities derived by Tercero et al. (2010). (b) Hot core component (dsou = 10 00, vfwhm = 7 km s 1 ) column density derived by Kolesniková et al. (2014). (c) Hot core component (dsou = 6 00, vfwhm = 8.6 km s 1 ) column density derived by Crockett et al. (2014). (d) Hot core component (dsou = 10 00, vfwhm = 10 km s 1 ) column densities derived by Esplugues et al. (2013). (e) Hot component (dsou = , vfwhm = 7 10 km s 1 ) column densities derived by Belloche et al. (2013). ( f ) Warm (60 K) component (dsou = , vfwhm = 6 8 km s 1 ) column densities derived by Belloche et al. (2013). (g) Hot component (dsou = , vfwhm = km s 1 ) column densities derived by Belloche et al. (2013). (h) Cold component (dsou = 30 00, vfwhm = km s 1 ) column densities derived by Belloche et al. (2013). (i) Marcelino et al. (2005). ( j) Cernicharo et al. (2012). Fig. 3. Observed data of Orion KL, Sgr B2, and B1-b taken with di erent instruments (histogram black spectrum) together with the synthetic ISMS spectra obtained 2016 (Urbana) using the column densities given as upper Valerio limits in Table Lattanzi 2 (thin red curve). The synthetic total model for the 30June m data 21, of

17 Conclusions New THz measurements for HSO radical Excellent test for quantum chemical calculations Deep search in astronomical sources No radioastronomical detection (so far) HSO has not been included in chemical models CH3 S + O might produce HSO yield of HSO might be too low for detection S-chemistry in space is very active and intriguing Extending astrochemical models to new S-species Laboratory work on new sulfur molecules (ions? radicals?)