LASER INDUCED FLUORESCENCE SPECTROSCOPY OF THE Si NSi

LASER INDUCED FLUORESCENCE SPECTROSCOPY OF THE Si. NSi RADICAL II: IDENTIFICATIONS OF THE A 2 A 1, B 2 B 1, AND D 2 Sg+ STATES C. MOTOYOSHI, Y. SUMIYOSHI, Y. ENDO Department of Basic Science, The University of Tokyo, Tokyo 153 -8902, Japan M. FUKUSHIMA, T. ISHIWATA Faculty of Information Sciences, Hiroshima City University, Hiroshima 731 -3194, Japan

Background of the Study Observation of LIF spectra of species containing Si and N in the near UV region　(30, 000 – 34, 000 cm– 1) Assigned the species to be linear Si. NSi for the 2 D – 2 P system (previous talk) u g However, there remained more vibronic bands, which could not be assigend to the 2 Du – 2 Pg system

Low-resolution LIF spectrum vibronic bands for the 2 Du– 2 Pg system vibronic bands with shorter lifetimes (c. a. 50 ns)

Ab initio calculations MRSDCI+Q / cc-p. VTZ (9 e in 9 o) 7 sg 3 pu 2 pg X 2 Pg 5 su 1 2 Pu C 2 D u D 2 S g+

High-resolution LIF spectrum G. S. of the observed bands are that of Si. NSi P–P and S–P type vibronic bands were observed

Constants for the new bands (cm-1) Pu Pu Tv 30890. 051(1) 31116. 5016(9) DE 0 226. 45 Aveff 0 0 Bveff 0. 11469(4) 0. 11677(2) 104 qv - 2. 2(1) - 4. 85(4) 0. 008 0. 007 s Tv DE Bveff s unresolved spin components ⇒ vibronic P levels of a S electronic state Su + 31729. 173(1) 31978. 677(1) 32336. 393(2) 839. 12 1088. 63 1446. 34 0. 11287(2) 0. 11484(3) 0. 11297(3) 0. 009 0. 007 0. 021

(cm-1) 32400 The D 2 Sg+ state Su + (101) predicted Te = 31300 cm-1 +n 1(Sg) 32000 31800 Su + (021) Su + (001) vibronically allowed transitions (only u vibronic levels are seen) +n 3(Su) 31200 31000 30800 Fu Pu Dg Sg + (030) (020) Pu (010) Sg + (000) Forbidden due to centrosymmetry (g/u)

Rotational constants for the D 2 Sg+ state

Vibrational analysis for the D 2 Sg+ state All vibronic energies are reproduced within 1 cm– 1 Te w 1 (cm-1) 29828(2) 608. 0(5) (cm-1) Be 0. 1132(2) a 1 0 (fixed) w 2 w 3 148(2) 959. 6(7) a 2 x 22 - 5. 8(3) a 3 - 0. 00099(4) 0. 00085(9) s 0. 65 s 0. 00008 The D 2 Sg+ state has shallower bending potential curve than that of the C 2 Du state (w 2 = 233 cm-1).

Low-resolution DF spectra C 2 D u → X 2 Pg D 2 S g + → X 2 Pg

High-resolution DF spectra (030)Pu pumped (010)Pu pumped

Observation of the A 2 A 1 and B 2 B 1 states B 2 B 1 D(021) Fluorescence D(010) pump 1 2 Pu A 2 A B 2 B 1 1 D(030) Linear The energy at the linear geometry (12 Pu) is estimated to be 13800 cm– 1 A 2 A 1

Potential energies for the A 2 A 1 and B 2 B 1 states MRSDCI+Q / cc-p. VTZ (11 e in 9 o) B 2 B 1 A 2 A 1 2 B X 2 P g 2 A 2 A 1 2 A 2 Ornellas and Iwata, J. Phys. Chem. 100, 10919 (1996) low lying bent isomer

Low-resolution LIF spectrum in the visible arrows indicate bands containing Si and N atoms

DF spectra from the visible bands

Analysis of the ground vibronic state Observed levels when the 13363 cm-1 band was pumped (in cm-1) Level o. –c. Assignment 0 (000)P 1/2 838 - 0. 2 (060)m. P 1/2 140 - 1. 8 (000)P 3/2 838 - 1. 3 (060)m. P 3/2 268 – ? 874 – ? 285 - 3. 4 (020)m. P 1/2 1039 2. 9 (040)k. P 3/2 310 1. 0 (020)m. P 3/2 1055 3. 8 (040)k. P 1/2 534 1. 3 (040)m. P 3/2 1118 1. 8 (080)m. P 1/2 557 - 2. 2 (040)m. P 1/2 1134 3. 1 (040)k. P 3/2 605 - 2. 8 (020)k. P 1/2 1389 - 3. 5 (080)m. P 3/2 631 2. 5 (020)k. P 3/2 1505 - 3. 7 (060)k. P 1/2 0 Newly obsered Analyzed using the RT 3 program (He and Clouthier, CPC 178, 676 (2008)) The determined parameters for the ground state (cm-1) w 2 e 187. 8(3) 0. 48(9) ASO 155(2) s 2. 8

Conclusions new band system, D 2 Sg+, has been assigned, which becomes allowed by the vibronic coupling. l. A l. Dispersed fluorescence spectra from the D state showed new electronic states, which were assigned to states with bent structures (A 2 A 1 and B 2 B 1 states). l. Low-resolution LIF spectrum for the visible system was observed. l. Dispersed fluorescences to higher vibronic levels for the ground state have been observed by exciting this system.