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High-Resolution Spectroscopic Studies of Reaction Intermediates relevant to Atmospheric Chemistry Yasuki Endo Department of Basic Science The University of Tokyo June/18/2014 ISMS 2014 Urbana

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Main Research Interests High-resolution spectroscopy of short lived reactive species, and complexes FTMW spectroscopy : Observe pure rotational transitions LIF spectroscopy : Electronic transitions Short lived species in the gas phase esp. produced in a supersonic jet Carbon chain molecules Oxygen bearing species Radical complexes

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Vis-UV Laser spectroscopic system YAG Laser pumped dye lasers with resolution up to 0.02 cm -1

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FTMW spectrometer Balle-Flygare type FTMW spectrometer Observe pure rotational transitions in the 4 40 GHz region

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Pulsed Discharge Nozzle Pulse Valve Pulsed electric discharge 1.02.0 kV, 0.2 msec Free radicals Discharge samples containing appropriate parent molecules in Ar or Ne (0.2 0.5 %) to produce target species Radical compexes

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FTMWmmW Double Resonance Method pump source PDN Sample MW cavity pulsed MW mm-wave as well as cm-wave sources can be used for the pump radiation. It is even possible to use optical or IR sources.

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Oxygen Bearing Short lived Species Species with more than one oxygen atoms HOOH, HOO, FOO, O 3 (well known) X-OO, CH 3 OO, HOOOH, HOOO, (oxygen chain species cf. carbon chain species) HOCO, H 2 CO 3, HCO 3, CH 2 OO, CH 3 CHOO CH 2 CHO, CH 2 CCHO Oxygen bearing radical complexes H 2 OOH, ArHO 2, HO 2 H 2 O COHOCO, H 2 OHOCO CH 2 OOH 2 O important in atmospheric chemistry

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Studies of the HOCO Radical and the Carbonic Acid Important players in atmospheric chemistry CO, CO 2 H 2 O, OH, HO 2 Oxidation reaction of CO OH + CO OHCO (1) HOCO CO 2 + H Hydration of CO 2 CO 2 + H 2 O CO 2 H 2 O (2) H 2 CO 3 (1) M. I. Lester, B. V. Pond, D. T. Anderson, L. B. Harding, A. F. Wagner, J. Chem. Phys. 113, 9889 (2000). (2) K. I. Peterson, W. Klemperer, J. Chem. Phys. 80, 3439 (1984).

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Oxidation reaction of CO Relative energy (kcal/mol) 30 20 10 0 10 t-HOCO (TS4) t-HOCO (TS1) c-HOCO (TS1) OHCO OH+CO H + CO 2 t-TS C 2v M c-HOCO (TS2) C 2v TS cis-HOCO trans-HOCO OH + CO CO 2 + H reaction

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trans-HOCO and cis-HOCO trans-HOCO Metastable state No gas phase spectra The most stable state Gas phase spectra known cis-HOCO 7.6 kcal/mol 1.8 kcal/mol

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Spectra of cis- and trans-forms a = 1.3 Debye a = 2.5 Debye 22564.522565.5 22113.5 22114.5 200 Iterations 1 01 0 00 J=1.50.5, F=21 cis-HOCOtrans-HOCO 1 4.5 Observed for the first time Discharge a mixture of CO and H 2 O in Ar

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Molecular Structures of HOCO cis-HOCO trans-HOCO Data from HOCO and DOCO Red: assumed

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Observation of COtrans-HOCO 6 06 5 05 finally 21 a-type transitions 2 b-type transitions has been observed

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Determined Structure of COHOCO 2.165 176.6 exp. ab inito A 33915.14(2) 33388 B 1273.450(1) 1280 C 1223.250(1) 1233 RCCSD(T) / aug-cc-pVTZ Carbon side is bonded Fairly short bond length

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Possible Existence of the HOCOH 2 O Complex cis-form of HOCO S. Aloisio, J. S. Francisco, J. Phys. Chem. A104, 404 (2000). Contribution of the existence of water on the oxidateion of CO

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Cyclic Structure of the H 2 OHO 2 Complex O1H3: 1.795 Fairly short cf. 2.019 (H 2 O) 2 K. Suma, Y. Sumiyoshi, and Y. Endo, Science 311, 1278 (2006)

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Structures of the H 2 OHOCO Complexes and their Relative Energies

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Observed Spectra of H 2 Otrans-HOCO Two series with different hyperfine patterns

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Molecular Constants of H 2 Otrans-HOCO AAab initio a (B+C)/22450.080(1)2437.687(1)2503 aa 162.9162.9(2) bb 2.43(1) 1.63(5) cc -5.15-5.15(5) aFaF -3.12(6) -3.44(10) T aa 24.66(3) 24.87(14) T aa (H 2 O) 2.53(7) a RCCSD(T) / aug-cc-pVTZ

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Determined Molecular Structures 1.823 1.752 (ab initio) Very short hydrogen bond (c.a. 2.0 ) Binding energy: 8.8 kcal/mol (ab initio) RCCSD(T) / aug-cc-pVTZ

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Observation of the Carbonic Acid H 2 O + CO 2 H 2 OCO 2 complex studied by FTMW spectroscopy H 2 CO 3 carbonic acid not detected in the gas phase

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Past Theoretical Studies 3 isomers (1) cis-ciscis-transtrans-trans Stability (2) H 2 CO 3 + n H 2 O CO 2 + (n + 1) H 2 O half-life, n = 0: 0.18 million years n = 1: 10 hours n = 2: 2 minutes Endothermic for the production of H 2 CO 3 half-life (log t /s) (1) B. Jnsson et al, Chem. Phys. Lett. 41, 317 (1976). (2) T. Loerting et al., Angew. Chem., Int. Ed. 39, 891 (2000).

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Ab initio Calculations 0 00 0 90 180 11 22 cis-ciscis-transtrans-trans MOLPRO 2008.1 CCSD(T)/cc-pVTZ Energy [kcal/mol] 11 22

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Molecular Structure of cis-trans H 2 CO 3 122.9 126.8 1.188 r(C=O) : 1.202 (HCOOH) 1.208 (H 2 CO) r(CO) : 1.343 (HCOOH) 1.425 (CH 3 OH) (O=CO) : 124.9(HCOOH) 1.345 1.357 Although this is a higher energy isomer, it has a large dipole moment and is rather easier to detect

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Molecular Structure of cis-cis H 2 CO 3 125.7 1.202 r(C=O) : 1.202 (HCOOH) 1.208 (H 2 CO) r(CO) : 1.343 (HCOOH) 1.425 (CH 3 OH) (O=CO) : 124.9(HCOOH) 1.340 It is the most stable isomer. Spectra were weaker since the dipole moment is smaller.

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Isomers of H 2 CO 3 0 00 0 90 180 11 22 cis-ciscis-transtrans-trans No spectrum was observed for the trans-trans isomer since the barrier to the cis-trans form is so low.

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Detection of Bicarbonate Radical Slightly exothermic (RCCSD(T)/cc-pVTZ)

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Observed Spectral Pattern Discharge H 2 O + CO 2 mixture, many paramagnetic lines

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An Example of the Observed Line 1000 times accumulation 2 02 1 01 J = 2.5 1.5 F = 3 2 In general, signals were very weak

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Determined Molecular Constants for HCO 3 exp.ab initio a FCO 2 b A13725.26(5)1392813752.2 B11263.93(4)1119811310.3 C 6170.11(4)6207 6192.8 aa 130.1(3) -83.4 bb 675.9(3) -794.7 cc 47.57(4) -44.2 aFaF 9.96(5) T aa 5.60(3) T bb 0.68(3) a RCCSD(T)-F12a / aug-cc-pVTZ b L. Kolesnikova et al., JCP 128, 224302 (2008)

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Detection of CH 2 OO Criegee Intermediate (CI): R 1 R 2 COO (carbonyl oxide) Intermediate in the ozonolysis process of alkene + O 3 Ozonolysis Process of Alkene: First proposed by Rudolf Criegee Justus Liebig Ann. Chem. 564, 9 (1949). Angew. Chem., Int. Ed. Engl. 14, 745 (1975).

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Previous studies of CH 2 OO Gas-phase Spectra of CH 2 OO M. I. Lester group JACS 134, 20045 (2012). Y.P. Lee group Science 340, 174 (2013). No direct information for the structure B-state: Repulsive

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Observed Spectra of CH 2 OO CH 2 OO: 1 01 -0 00 CH 2 OO: 2 02 -1 01 FTMW spectrumFTMW-mmW DR spectrum 400-shots (CH 2 Br 2 + O 2 ) disch. now (CH 2 I 2 + O 2 ) disch. : very strong signals

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Determined Molecular Structure of CH 2 OO Ab initioFit 1Fit 2 r OO / 1.3411.344(1)1.345(3) r CO / 1.2681.274(1)1.272(3) r CH (cis) / 1.0821.147(15)1.094(1) r CH (trans) / 1.0791.118(7)1.088(4) OOC / deg. 117.95118.06(2)118.02(3) OCH (cis) / deg. 118.6108.2(22)118.0(6) OCH (trans) / deg. 114.9120.8(13)114.9(fix) fit / MHz 1.112.83 long O-O bond zwitterion like structure Structure from CH 2 OO CD 2 OO CH 2 18 O 2 CD 2 18 O 2

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More Papers for CH 2 OO FTMW, more isotopologues, refined structure M. C. McCarthy et al., J. Phys. Chem. Lett., 4, 4133 (2013) Sub-mm wave spectrum A. M. Daly et al., J. Mol. Spectrosc., 297, 16 (2014)

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Detection of Methyl Derivatives Internal Rotation of the Methyl-tops Higher Barrier due to the interaction with O atom Lower Barrier 3.7 kcal/mol higher in energy

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Rotational Transitions of syn-CH 3 CHOO UV absorption by J. M. Beames et al. JCP 138, 244307 (2013) red: FTMW blue: FTMW-mmw-DR (CH 3 CHI 2 + O 2 ) disch.

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Observed Transitions of syn-CH 3 CHOO (a) FTMW spectrum (b) FTMW-mmw-DR spectrum Very small splittings for the internal rotation

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Rotational Transitions of anti-CH 3 CHOO red: FTMW blue: FTMW-mmw-DR Signals are 1/3 1/4 times weaker than those of syn- CH 3 CHOO

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Observed Transitions of anti-CH 3 CHOO Observed by FTMW spectroscopy Relatively Large AE splittings EA

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Determined Parameters for CH 3 CHOO

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Water Complex of CH 2 OO 1.872 2.114 Cyclic Structure (CCSD(T)/aug-cc-pVTZ) Double hydrogen bonds cf. H 2 OHOO Relatively short OO...HO bond length Enhance hydrogen migration to produce the OH radical

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Rotational Transitions of CH 2 OOH 2 O (CH 2 I 2 + O 2 + H 2 O) disch. red: FTMW blue: FTMW-mmw-DR Tansitions of CH 2 OOD 2 O were also observed (detection was confirmed)

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Determined Parameters for the Water Complex

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Determined Structure 1.910 (1.872 ) 2.123 (2.114 ) The hydrogen bond is shorter than usual Cyclic structure like HO 2 H 2 O CH 2 OO: proton acceptor

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Conclusions for the Studies of Criegees The simplest Criegee, CH 2 OO, was identified by FTMW spectroscopy, and structure has been determined. Nakajima and Endo, JCP 139, 101103 (2013) Both syn- and anti-forms of CH 3 CHOO were identified, where barriers for the internal rotations were determined. Nakajima and Endo, JCP 140, 101101 (2013) CriegeeWater complex, CH 2 OOH 2 O, was identified by FTMW spectroscopy, and cyclic form was confirmed, which is expected to enhance the hydrogen migration producing the OH radical. Nakajima and Endo, JCP 140, 1034302 (2014)

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Other Studies Carbon chain species (FTMW and LIF) CCS, HCCN, CCCF, CCCCl, SiCCN, SiCCCN, SiCCH Vinoxy derivatives (FTMW and LIF) CH 2 =CHO, CH 2 =CHS, CHCH 3 =CHO, CH 2 =CCH 3 S, CH 2 =C=CHO Atomdiatom systems (FTMW) RgOH, RgSH, RgNO, RgCS

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Acknowledgement Prof. M. Nakajima (U. Tokyo) Criegees Prof. Y. Sumiyoshi (Gumma Univ.) Dr. T. Mori (Horiba Co. Ltd.)H 2 CO 3, HCO 3 Dr. T. Oyama (Tokyo Science Univ.)HOCO and other graduate students Financial Support JSPS funds