1. Vincent Sironneau, P. Chelin, F. Kwabia Tchana, I. Kleiner, J. Orphal, O. Pirali, J.-C. Guillemin, L. Margulès, R. Motiyenko, S. Cooke, W.J. Youngblood, A. Agnew, C.T. Dewberry Columbus 2010

2.  Produced by biomass burning  Involved in the photochemical oxidation of volatile organic compounds  Rapid photolysis  Lifetime in the atmosphere? (2 minutes*)  Detection? * W.D. Taylor, T.D. Allston, M.J. Moscato, G.B. Fazekas, R.Kozlowski, G.A. Takacs, Int. J. Chem. Kinet. 12 (1980) 231–240.

3.  Energy difference between the two isomers is approximately 275cm -1  cis-trans barrier height: 3786 cm -1  Internal rotation potential barrier:  cis isomer : 739 cm -1  trans isomer : 15 cm -1  Most studies concern cis-trans interconversion, photofragmentation, UV absorption spectrum cis-methyl nitritetrans-methyl nitrite J.B.P. da Silva, N.B. da Costa, M.N. Ramos, R. Fausto, J. Mol. Struct. 375 (1996) 153-180 B. J. van der Veken, R. Maas, G. A. Guirgis, H. D. Stidham, T. G. Sheehan, J. D. Durig, J. Phys. Chem. 94 (1990) 4029-4039 A. Untch, R. Schinke, R. Cotting, J.R. Huber, J. Chem. Phys. 99 (1993) 9553-9556 H.-M. Yin, J.-L. Sun, Y.-M. Li, K.-L. Han, G.-Z. He, S.-L. Cong, J. Chem. Phys. 118 (2003) 8248-8255

4.  Two isomers  Internal rotation of the methyl group  Hyperfine structure (quadrupole of nitrogen)  Low vibrational modes  Very weak torsional bands, not observed with standard sources  Not commercial

5.  Cis isomer: the barrier V 3 = 739 cm -1  Example for the 15 0,15 -15 0,15 line  v t = 0 the A and E lines separated by 60 kHz  v t = 1 the splitting E-A is 3.6 MHz  The splitting depends of the height of the barrier the higher the barrier is, the smaller the splittings are

6.  Trans isomer: the barrier V 3 = 15 cm -1 free rotor, quantum number “m” for the torsional state  872 MHz for the 2 02 -1 01 transition  Some low barrier molecules studied so far :  acetamide, V 3 = 25 cm -1 (JMS 2004)  para-tolualdehyde V 3 = 28 cm -1 Grabow et al WH07  meta-tolualdehyde V 3 = 35 cm -1, K. M. Hotopp D. S. Wilcox, A. J. Shirar, B. C. Dian, TC12, RH15  trans-methyl formate V 3 = 15 cm -1,Muckle et al, Columbus 2009

7.  Lines available in the literature for the cis:  60 lines for v t = 0 (J ≤ 20)  20 lines for v t = 1 (J ≤ 3)  20 for v t = 2 (J ≤ 3)  measurements/assignments errors: bad do-loops in v t =1  A few lines (about 30) for the trans J < 5 P.N. Ghosh, A. Bauder, H.H. Günthard, Chem. Phys. 53 (1980) 39–50 P.H. Turner, M.J. Corkill, A.P. Cox, J. Phys. Chem. 83 (1979) 1473-1482 L. M. Goss, C. D. Mortensen and T. A. Blake, J. Mol. Spectrosc., 225, 182-188 (2004)  Infrared spectra at low resolution of CH 3 ONO and CD 3 ONO (1982)  Only one study at high resolution ν 8 cis-CH 3 ONO (2004)

8.  Presently the analysis deals only with the cis-CH 3 ONO  First part:  New microwave measurements  Between 1 and 21 GHz, S. Cooke, W.J. Youngblood, A. Agnew, C.T. Dewberry, University of North Texas (TC04)  Between 75 and 465 GHz, L. Margulès, R. Motiyenko, Phlam Lille  FIR in the French Synchrotron Soleil, V. Sironneau, P. Chelin, F. Kwabia Tchana, I. Kleiner, J. Orphal, O. Pirali, J.-C. Guillemin  Second part:  MIR region at LISA Créteil, V. Sironneau, P. Chelin, F. Kwabia Tchana, I. Kleiner, J.-C. Guillemin

9. Laurent Margulès and Roman Motiyenko Cis isomer: v t =2 14 ~ 213 cm -1 10 ~ 346 cm -1 v tors ~ 170 cm -1 ? (previous MW studies) v tors ~ 214 cm -1 (this work) Trans isomers: v t =0, v t =1 14 ~ 230 cm -1 ? 10 ~ 379 cm -1 v tors ~ 26 cm -1 ?(E) and 80 cm -1 ?(A)

10.  Fit done with the Belgi-Cs program  All parameters are in the Rho Axis Method  Values in cm -1 except ρ which is unitless  Number of lines  707 for v t =0  715 for v t =1  1 ≤ J ≤ 40  0 ≤ K a ≤ 23  31 parameters  34kHz close to the experimental accuracy J. T. Hougen, I. Kleiner, and M. Godefroid, J. Mol. Spectrosc. 163 (1994) 559-586 nlm a OperatorParameter b values 220(1/2)(1-cos3γ)V3V3 739(3) Pγ²Pγ²F6.183(18) 211PγPaPγPa ρ0.0861038(82) 202Pa2Pa2 A RAM 0.591655(15) Pb2Pb2 B RAM 0.332055(13) Pc2Pc2 C RAM 0.1882082(31) (P a P b +P b P a )D ab 0.16835(1) 440Pγ4Pγ4 k4k4 -0.405(13) ×10 -3 (1/2)(1-cos6γ)V6V6 76.26(41) 422P γ ² P a 2 GvGv -0.5245(73) ×10 -4 sin3γ (P b P c +P c P b )D bc 0.001352(85) (1-cos3γ)P a 2 k5k5 0.013938(31) (1-cos3γ)P 2 FvFv -0.00878(7) 422(1-cos3γ) (P a P b +P b P a )d ab 0.010475(12) 2 P γ ²(P b 2 -P c 2 )c1c1 -0.251(10) ×10 -5 413P γ P a P 2 LvLv 0.955(16) ×10 -5 P γ P a 3 k1k1 0.722(27) ×10 -5 P γ {P a (P b 2 -P c 2 )}c4c4 0.1877(82) ×10 -5 404- P 4 ΔJΔJ 0.2613(30) ×10 -6 - P 2 P a 2 Δ JK -0.30(35) ×10 -7 - P a 4 ΔKΔK 0.210(69) ×10 -5 - 2P 2 (P b 2 -P c 2 )δJδJ 0.855(15) ×10 -7 - {P a 2,(P b 2 -P c 2 )}δKδK 0.378(13) ×10 -6 P 2 (P a P b +P b P a )D abJ 0.103(12) ×10 -6 P a 2 (P a P b +P b P a )D abK -0.10357(8) ×10 -5 606- {P a 2,(P b 2 -P c 2 )}φKφK 0.39(2) ×10 -11 642(1-cos6γ)P 2 NVNV 0.002719(44) P γ 4 P 2 MVMV -0.457(10) ×10 -7 P γ 4 (P b 2 -P c 2 )c3c3 0.1856(69) ×10 -7 624(1-cos3γ) P 2 (P a P b +P b P a )d abJ -0.401(11) ×10 -8 (1-cos3γ) P a 2 (P a P b +P b P a )d abK -0.429(28) ×10 -7

11. O.Pirali, V. Sironneau, P. Chelin, J. Orphal Goals: - Very weak torsional bands 150cm -1 (hot band progressions) 170cm -1 (previous MW studies) 214cm -1 (our study) - High J and K a values in the pure rotational spectrum Pure rotational spectrum of CH 3 ONO recorded at the French Synchrotron Soleil

12.  P = 0.11 mbar, L = 150 m Res = 0.0011cm -1  No resolved internal rotor splittings in the FIR for the cis-isomer  Waston type Hamiltonian in A reduction, I r representation (Maki’s code) Ghosh et al.[2]Goss et al. [14]This work A0.6762191(120)0.6762192(16)0.67621038(34) B0.2481020(1)0.2481021(5)0.24809892(21) C0.1878160(3)0.1878163(5)0.18781343(24) ΔJΔJ 2.25E-07(7)2.2407E-07(76)2.23938E-07(67) Δ JK -4.30E-07(43)-5.11E-07(69)-5.1759E-07(25) ΔKΔK 1.834E-06(70)1.892E-06(17)1.89466E-06(33) δJδJ 7.0E-08(3)6.654E-08(50)6.7014E-08(11) δKδK 1.8E-07(7)2.42E-07(20)2.4237E-07(34) ΦJΦJ -1.45E-13(6) Φ JK 8.37E-13(45) Φ KJ -1.09E-11(1) ΦKΦK 2.569E-11(9) rms110kHz0.000440.00012 N.of lines31 MW32 MW+ 634 IR2164 IR J range0-184-4712-81 K a range0-70-170-48 Values in cm -1

13. resolution of 0.0019cm -1 P= 0.3 Torr, L=3.2m resolution of 0.003cm -1 P=0.05 Torr, L=19.2m

14.  Goss et al. Watson type Hamiltonian (634 lines) rms = 0.00044cm -1  But splittings for the low values of J and K a and they are not included in their fit  With BELGI-Cs (708 + 118 internal rotor splittings lines) rms = 0.00048cm -1 (2 ≤ J ≤ 50, 0 ≤ K a ≤ 22)  But V 3 = 623cm -1 (739cm -1 for the ground state) and F = 6.82cm -1 (6.18cm -1 for the ground state) effectives values P.N. Ghosh, H.H. Gunthard, Spectrochim. Acta 37A (1981) 347–363 L. M. Goss, C. D. Mortensen and T. A. Blake, J. Mol. Spectrosc., 225 (2004) 182-188

15.  Around 650 assigned lines with a rms 0.00046cm -1  The internal rotor splittings are not included yet into the fit

16.  Microwave analysis of the v t =0 and v t =1 for cis-CH 3 ONO (1422 lines rms = 34kHz J up 1 to 40, BELGI code) Global analysis MW+FIR presents status : 3482 lines 1422 MW (707 in v t =0 and 715 in v t =1) + 2060 FIR ( 1342 in v t =0 and 718 in v t =1) rms = 35kHz, 0.00018cm -1  FIR pure rotational spectrum of cis-methyl nitrite (2164 lines rms = 0.00012 cm -1 J = 12 up to 81, Maki’s code)

17.  Plan to search v t =2 for the cis-isomers (expected perturbations with ν 14 and ν 10 )  Need MW data for low J and K a value to start the study of trans-methyl nitrite…

18.  For the ν 8 band, our effective model reproduce well the internal rotor splittings (Spectral range for an atmospheric detection?)  The analysis of the ν 9 band is still in progress: vibration-rotation-torsion interactions need to be modeled!

19.  Solution 1 : 11 g of sodium nitrite + 6,4 g of methanol in 50 mL of water  Solution 2 : 8 g of sulfuric acid + 14 mL of water  Pour the solution 2 mL by mL in the first one  In 800-900 mbar nitrogen atmosphere  Methanol is the principal impurity  Methyl nitrite was condensed in a trap at -80 °C (pale yellow liquid) In spite of several purifications (distillation) a trace of methanol was still present