Time-resolved Fourier transform infrared emission spectroscopy of laser ablation products K. Kawaguchi1, N. Sanechika1, Y. Nishimura1, R. Fujimori1, T. N. Oka2, Y. Hirahara2, A. I. Jaman3, and S. Civis4 Okayama University1 Nagoya Univversity2 Saha Institute3 Heyrovsky Institute4

Laser ablation - spectroscopy LIF : metal compounds: YO, YF (1993) FT MW: metal compounds: YO, LaO, ZrO, HfO biomolecules: amino acids Infrared : diode laser : C5, C7, C9 many matrix isolation studies grating : YO emission Recently high repetition rate laser (1-10 kHz) Application to TR-FTS (1) atomic spectra (2) reaction product of C and O2

Block diagram of TRFTS system Laser trigger Nd:YLF laser Laser ablation ADC 4322 16 bit ≲ 2 MHz New method SX is replaced by FPGA (Field Programmable Gate Array)

Timing diagram for TRFTS Scan siganal 200 msec He-Ne laser 2nd scan 1st scan Trigger for Pulse laser sampling 64 spectra 64 interferograms ½ sampling : sampling 5 kHz, pulse laser 2.5 kHz

Laser ablation Nd:YLF laser 527 nm 1.6 mJ/pulse 2.5 kHz Motor To FTS 5 rot/sec To FTS lens Metal rod Actuator

Emission spectrum from laser ablation of Fe 2742:g7D- s6D6p7Do 2743:g7D- s6D6p7Fo 2781: 4f-5g 2778: 5d-5f 2662: 5p-6s (Nave et al. 1994) 1850-3950 cm-1 Total 137 lines 67 un-identified

Emission spectrum of Fe I Absorption Spectrum of Sun (ATMOS) Emission from iron ablation Nave et al. APJS 94, 221(1994) Hollow cathode Fe I 3d 64s(6D)4f – 3d 64s(6D)5g 61800 cm-1 high

Emission spectrum from ablation of iron SUN absorption a b Emission from iron ablation a:5d-5f b:v 5P0-e 3P New line

Ablation from brass Cu : U Cu 6s-6p

Time profiles of ablated Fe and Cu

Time profile of Cu line (2497.8 cm-1)

Diffusion process Boltzmann equation Imajyo, Higuchi, Yamakita, Bunko Kenkyu, 55,394(’06) Collision cross section A:0.25 s B:0.4 “ C:0.6 “ D:0.8 “ E:1.0 “ s=4.16x10-19 m2

CO emission C(gas) + O2 -> CO + O -578 kJ/mol (48258 cm-1) v=1-0 O2 =500 mTorr C(gas) + O2 -> CO + O -578 kJ/mol (48258 cm-1) Up to v=13-12, Eu=26000 cm-1 limited by InSb detector

Rotational distribution in v=6 Error:30K

Vibrational distribution CO (v) + CO (v=0) ⇆ CO (v-1) + CO(v=1) Vib. relax slow 10-12 cm3s-1 5 mTorr CO 5.8 msec　 non-equilibrium

Vibrational relaxation v=6-5 P(8) 160 mTorr CO t=180 msec

Summary laser ablation products monitored by TR-FTS (1) High energy states of Fe I related to solar absorption spectrum : comparison with discharge (2) Diffusion process : collisional cross section (3) Reaction of O2 and carbon non-equilibrium vibrational distribution