Jet-Cooled Spectroscopy of 1- Naphthylmethyl, 2-Naphthylmethyl & Acenaphthenyl Radicals Nahid...
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Transcript of Jet-Cooled Spectroscopy of 1- Naphthylmethyl, 2-Naphthylmethyl & Acenaphthenyl Radicals Nahid...
![Page 1: Jet-Cooled Spectroscopy of 1- Naphthylmethyl, 2-Naphthylmethyl & Acenaphthenyl Radicals Nahid Chalyavi.](https://reader036.fdocuments.net/reader036/viewer/2022062422/56649f335503460f94c509c2/html5/thumbnails/1.jpg)
Jet-Cooled Spectroscopy of 1-Naphthylmethyl, 2-Naphthylmethyl &
Acenaphthenyl Radicals
Nahid Chalyavi
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Astrochemical Significance of PAHs
Jenniskens P. et al., Ap.J., 183, 87, 1973
Diffuse Interstellar Bands
Cohen M. et al., A & A, 390, 147, 2002
Red Rectangle Bands
F.C. Gillett et al., Ap.J., 183, 87, 1973
Unidentified Infrared Bands Interstellar Dust Grain Model
Kwok, Nature 430, 985 (2004)
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3Kwok, Nature 430, 985 (2004)
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Resonance-Stabilized Radicals (RSRs)
Preferable product from decomposition of
stable species
Slower rate of reaction and dissociation
compared to localized radicals
Can reach high concentration in reaction
environment
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Supersonic Jet Expansion
High pressure gas (Ar)
Vacuum
Pulsed nozzle
cold molecules in centre of beam
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Detector
Source
Extractionof ions
Time-Of-Flight MS
Resonance-Enhanced Multiphoton Ionization (REMPI)
Ionisation continuum
l1
+e-
l2
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Laser-Induced Fluorescence (LIF) & Dispersed Fluorescence (DF) Spectroscopy
Vibrational Coordinate
Ener
gy
DF
Vibrational Coordinate
Ener
gyLIF
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1-Naphthylmethyl Radical LIF vs. REMPI
A' = 1.987 GHz A" = 1.996 GHzB' = 1.102 GHz B" = 1.121 GHzC' = 0.709 GHz C" = 0.718 GHz
Band Type: a/b=1.325Band Origin: 17240.68 cm-1
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Dispersed Fluorescence (DF)
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Comparison with RR and DIB Bands
The Red Rectangle Emission wavelength has been corrected for
the speed of nebulae (18.9 km/sec)
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2-Naphthylmethyl Radical LIF vs. REMPI
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Dispersed Fluorescence (DF)
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Comparison with RR and DIB Bands
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Acenaphthenyl Radical LIF vs. REMPI
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Dispersed Fluorescence (DF)
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Comparison with RR and DIB Bands
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Conclusions & Future Work
Jet-cooled spectroscopy of three resonance-stabilized radicals containing
naphthalene moiety has been studied
A coincidence is found between 1-naphthylmethyl radical origin transition and a
red rectangle emission band
The coincidence suggests that some structures similar to these radicals might be
the carriers of red rectangle bands
Consider other resonance-stabilized radicals with similar structures
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AcknowledgementsDr. Timothy SchmidtDr. Rob SharpDr. Masakazu NakajimaThe Laser Spectroscopy Group