FTIR Spectroscopy of the n4 bands of 14NO3 and 15NO3 (Okayama Univ., Hiroshima City Univ.) R. Fujimori, N. Shimizu, J. Tang, K. Kawaguchi, T. Ishiwata
Infrared study of NO3 K+1 Four fundamental bands n3+n4. n1 ; inactive n2 ; Friedl and Sander(1987) n3 ; very weak intensity n4 ; Only Matrix isolation observation (Beckers, Willner, Jacox. 2009) 1127 1492 K+2 n4. K+3 K Gr. DK=3 CD Present study ; first gas-phase spectroscopy of n4 Determination of C0 from DK=3 Combination Difference ( selection rule DK = ±1 for n4, combined with other measurements) Calculation of inertial defect
Experimental setup 0.006 cm-1 resolution Effective path length :48-m Liq. He Si bolometer
Detector part – Silicon Bolometer Dewar temperature 4.2 K to 1.7 K
Monitoring of NO3 concentration by HeNe laser Absorption spectrum of the NO3 B-X band Sander, J. Phys. Chem. (1986) discharge Off 10 % absorption Absorption of HeNe Laser (3-m path length) discharge On
Observed spectrum of 14NO3 radical
Analysis 1. n4 band 114 lines PP(N,K) K=5 ~ 29 2. DK=3 ground state combination differences n4 (365), n3+n4-n4 (1127), n3+n4 (1492) 3. n4 combination differences n3+n4-n4 (1127), n3+n4 (1492) 4. DK=0 ground state combination differences n3+n4 (1492) rQ(N+1,K) and rR(N,K) pQ(N-1,K) and pP(N,K)
Combination differences for DK=3 and n4 n3 + n4 13 14 n3 hot band of 15NO3 was newly observed 1127 cm-1 1492 cm-1 n4 13 14 n4 combination differences 365 cm-1 band Gr DK = 3 combination differences K = 12 15
Statistical weight in Analysis 1. n4 band 114 lines PP(N,K) K=5 ~ 29 Weight = 1 (accuracy 0.001 cm-1) 2. DK=3 ground state combination differences n4 (365), n3+n4-n4 (1127), n3+n4 (1492) Weight = 1/3 3. n4 combination differences n3+n4-n4 (1127), n3+n4 (1492) Weight = 1/2 4. DK=0 ground state combination differences n3+n4 (1492) Including diode laser data
14NO3 and 15NO3 molecular constants(1) (Ground state) 14NO3 15NO3 present previous present B 0.4585445(86) 0.4585485(63) 0.458613(14) C 0.2286679(57) [0.2292743] 0.2287127(89) DN ☓105 0.1092(13) 0.1113(12) 0.1090(25) DNK☓105 -0.2073(26) -0.2121(27) -0.2017(65) DK ☓105 0.1072(18) [0.1034] 0.0995(52) ebb -0.01621(20) -0.01649(13) -0.01549(26) ecc 0.00079(14) [0.0] [0.00079] DKx105(calc) 0.101 0.0977 sfit=0.0013 cm-1
14NO3 and 15NO3 molecular constants(2) (n4 state) 14NO3 15NO3 present previous present n0 365.48776(35) 365.48419(43) 360.20294(59) B 0.4592093(41) 0.4592222(60) 0.4592148(90) C 0.2282897(28) 0.2278233(40) 0.2283252(36) DN ☓105 0.0924(16) 0.1019(23) 0.0953(44) DNK☓105 -0.1643(41) -0.1953(58) -0.169(13) DK ☓105 0.0801(28) 0.0973(40) 0.0815(97) Cz -0.042984(14) -0.042063(15) 0.035723(23) hN☓105 -0.470(21) -0.431(28) -0.48(13) hK☓105 0.379(27) 0.382(36) 0.40(13) q4 0.013276(15) 0.013363(22) 0.013360(66) aeff -0.16581(44) -0.17016(36) -0.16606(50) ebb -0.015376(36) -0.015766(36)-0.014498(53) ecc 0.000761(26) [0.0] 0.000664(33)
Inertial defect of planar symmetric top molecule harmonic frequencies and z3 Jagod and Oka (1990, JMS) Check of vibrational assignment
Inertial defect in BF3 (example, data Maki et al. JMS ) Dobs=Ic-2 Ib amu Å2 v1 v2 v3 v4 obs calc obs-calc 0 0 0 0 0.1967 0.1961 0.0005 0.3% 1 0 0 0 0.1968 0.1961 0.0007 0.4% 0 1 0 0 0.0665 0.0763 -0.0097 13 % 0 0 1 0 0.2436 0.2573 -0.0137 5 % 0 0 0 1 0.3936 0.3910 0.0026 2 0 0 1 0.4222 0.3910 0.0311 0 2 0 0 -0.0639 -0.0436 -0.0204 30%(max) 0 0 2 0 0.2900 0.3184 -0.0284 0 0 0 2 0.5894 0.5859 0.0035 0 0 0 2 0.5916 0.5859 0.0056 1 1 0 0 0.0798 0.0763 0.0035 1 0 1 0 0.2228 0.2573 -0.0345 1 0 0 1 0.4079 0.3910 0.0169 0 1 0 1 0.2619 0.2712 -0.0093 0 0 1 1 0.4278 0.4522 -0.0244
Inertial Defects D (amu Å2) of NO3 D=Ic - 2Ib Obs. Calc. O-C Gr. 0.206 0.223 -0.017 (0001) 0.434 0.437 -0.003 (1001) 0.474 0.437 0.037 (00031 1.091 0.864 0.227 (0011) 0.367 0.487 0.120 x3 + x4 = 0 (D3h ) n1 (1050), n2 (762) n3 (1127), n4 (365) 8 % 0.7 % 21 % 24 % n4 n1+n4 3n4 n3+n4 1492 band x3 + x4 ≠ 0 not in D3h (Jahn-Tellar effect ) large p34 [splitting in K=1], eaa-ebb≠0 In this calc, if n3 = 1492, D3 calc = 0.237 Disagreement with observed D (35%)
Relative infrared intensity n3+n4(1492 band) = 1.00 band Obs. Calc.(Stanton) ν4 (365 cm-1) 0.59 0.26 3ν4 (1173) 0.03 0.06 ν1+ν4 (1413) 0.12 0.31 ν3+ν4 (1492) 1.00 1.00 ν3+2ν4(1927) 0.65 0.13 J. F. Stanton, Molecular Physics, 107.1059 (2009) Agreement within factor 2 except for ν3+2ν4
Summary 1. Measurement of the n4 band of NO3 Present 365.7871 cm-1 Matrix 365.6 cm-1 Isotope shift (14N - 15N) = 5.5851 cm-1 2. Determination of C0 0.2286321 (67) cm-1 14NO3 0.228674 (11) cm-1 15NO3 3. Calculations of Inertial defect
Inertial defect in SO3 (example, data Maki et al. JMS ) v1 v2 v3 v4 obs calc obs-calc 0 0 0 0 0.1576 0.1585 -0.0008 0 1 0 0 0.3089 -1.0765 1.3855 0 0 1 0 0.1776 0.1732 0.0044 0 0 0 1 0.2245 0.9196 -0.6951 0 0 0 1 0.3782 0.9196 -0.5414 0 2 0 0 -0.0975 -2.3115 2.2141 0 0 2 0 0.1981 0.1880 0.0102 0 0 0 2 0.5424 1.6808 -1.1384 0 0 0 2 0.5445 1.6808 -1.1363 1 1 0 0 0.3317 -1.0765 1.4082 0 0 1 0 0.1827 0.1732 0.0095 1 0 0 1 0.2041 0.9196 -0.7156 0 1 0 1 0.2216 -0.3153 0.5370 0 0 1 1 0.2544 0.9344 -0.6800 0 0 0 3 0.3679 2.4420 -2.0741 0 1 0 2 0.4369 0.4458 -0.0090 0 2 0 1 0.5243 -1.5503 2.0746 0 1 1 0 0.2999 -1.0618 1.3616 Dobs=Ic-2 Ib amu Å2