Matrix isolation spectroscopy of laser ablated carbon species in Ne, D2, and H2 matrices

Abstract

The results of matrix isolation experiments on carbon atoms and clusters generated by pulsed laser ablation of graphite are presented. C3 and other Cn clusters are observed by their infrared absorptions in Ne, ortho-D2, and para-H2 matrices. CH4 molecules and CH3 radicals are observed in H2 matrices, as are CD4 molecules in D2 matrices. The CH4:C3 concentration ratio in the H2 matrices is seen to increase dramatically with increasing ablation laser intensity. These results confirm and illuminate previous work by Miki, Wakabayashi, Momose, and Shida [J. Phys. Chem. 100, 12135 (1996)] on Cn doped cryogenic para-H2 samples produced by combined laser ablation and gas condensation in an enclosed cell. Their nonobservation of any hydrocarbon reaction products (particularly CH4) is explained by the lower intrinsic absorption strengths of the CH4 vs C3 vibrational transitions, and by attributing a low C1:C3 production ratio to the ablation process under their laser intensity and wavelength conditions.

Anharmonic Spectroscopic Study of the Ground Electronic State of Various C4Radical Isotopomers

“…5 ¼ 176 cm À1 . The 3 is off by about 400 cm À1 from the experimental determinations (1548Y1539 cm À1 ; Heath & Saykally 1991;Smith et al 1994;Forney et al 1995;Tam et al 1997;Szczepanski et al 1996). A large and significant improvement of this frequency is obtained with the UCCSD( T) and CASSCF methods (1554.6 and 1669.9 cm À1 , respectively).…”

“…h Diode laser absorption (gas phase) from Heath & Saykally (1991). i IR (Ne matrix, solid Ne) from Smith et al (1994), Forney et al (1995), and Tam et al (1997). j IR (Ar matrix) from Shen & Graham (1989).…”

“…Briefly, the infrared ( IR) spectrum of l-C 4 trapped in Ar matrix by Shen & Graham (1989) and the gasphase IR spectrum of l-C 4 by Heath & Saykally (1991) have identified the antisymmetric CC stretching 3 fundamental at 1543.4 cm À1 in matrix and at 1548.9 cm À1 in the gas phase. Later studies performed in the Ne matrix (Smith et al 1994), in solid neon (Forney et al 1995), and in Ne, ortho-D 2 , and para-H 2 matrices (Tam et al 1997) placed the origin 3 band at 1547 cm À1 , whereas the cooled Kr matrix C 4 isolation study of Szczepanski et al (1996) has located it at lower energies (1539 cm À1 ). The situation is, however, rather critical for the other modes which are known with relatively large error bars, making the unequivocal assignment of some interstellar bands difficult.…”

Anharmonic vibrational frequencies and vibrationally-averaged structures of key species in hydrocarbon combustion: HCO+, HCO, HNO, HOO, HOO–, CH3 +, and CH3

“…Those of the umbrella (OPLA) ( 2 ) [210,216,217] and anti-symmetric C-H stretch ( 3 ) [218][219][220][221][222][223] were also measured accurately. For the deformation ( 4 ), approximate values of its frequency were obtained [224][225][226][227] by the matrix isolation technique and they were in the range of 1396 to 1403 cm À1 . No gas-phase measurements have so far been reported for this mode.…”

Electronic spectroscopy of B atoms and B2 molecules isolated in para-H2, normal-D2, Ne, Ar, Kr, and Xe matrices

“…73 The TASSPI geometry is distinguished by having the laser ablation process occur in a separate differentially pumped vacuum chamber; resulting in enhanced control over the ablation process as compared to ablation in the CLOSE geometry. First, by virtue of the differential pumping arrangement, we expect greatly reduced interactions between uncondensed matrix host gases and the laser ablated plume.…”