An LIF characterization of supersonic BO (X2Σ+) and CN (X2Σ+) radical sources for crossed beam studies

Abstract

Various ablation sources generating supersonic boron monoxide (BO; X(2)Σ(+)) radical beams utilizing oxygen (O(2)), carbon dioxide (CO(2)), methanol (CH(3)OH), and water (H(2)O) as seeding gases were characterized in a crossed molecular beams setup by mass resolved time-of-flight spectroscopy and spectroscopically via laser induced fluorescence. Intensities of the sources as well as rovibrational energy distributions were analyzed. The molecular oxygen source was found to produce excessive amount of an unwanted BO(2) byproduct. Internal vibrational energy of boron monoxide generated in the water and methanol sources was too high to be considered for the study of dynamics of ground state radicals. The best combination of intensity, purity, and low internal energy was found in the carbon dioxide source to generate boron monoxide. We successfully tested the boron monoxide (BO; X(2)Σ(+)) radical beam source in crossed beams reactions with acetylene (C(2)H(2)) and ethylene (C(2)H(4)). The source was also compared with supersonic beams of the isoelectronic cyano (CN; X(2)Σ(+)) radical.

A combined crossed molecular beams and theoretical study of the reaction CN+C2H4

“…6500 K, while the rotational distribution is bimodal, with two peaks around N = 6 and 40 [32]. This is in contrast to the CN beam employed by Kaiser and coworkers [38], where the radical rovibrational distributions are substantially colder [39].…”

A crossed beam and ab initio investigation on the formation of vinyl boron monoxide (C2H3BO; X1A′) via reaction of boron monoxide (11BO; X2Σ+) with ethylene (C2H4; X1Ag)

“…53 Our LIF study conducted earlier for our boron monoxide radical source shows that 11 BO is efficiently cooled by the supersonic expansion and only has a maximum of 2 kJ mol À1 of internal energy. 38 Considering that ethylene is efficiently cooled by the supersonic expansion, we can subtract the maximum internal energy from the reaction exoergicity to obtain a value Having identified the product to be exclusively vinyl boron monoxide (C 2 H 3 11 BO) plus atomic hydrogen, we propose the underlying reaction dynamics. A comparison of the structures of the reactants with the polyatomic product, we can see that the hydrogen atom in ethylene is effectively replaced by the 11 BO group.…”

“…The fluorescence was detected by a Hamamatsu R955 photomultiplier tube (PMT) filtered by a band pass filter centered at 495 nm for detection of (2,0) fluorescence. 38 The spectra were analyzed using the diatomic spectral simulation program developed by Tan. 39 The reaction products were monitored using a triply differentially pumped quadrupole mass spectrometer (QMS) in the time-of-flight (TOF) mode after electron-impact ionization of the neutral molecules at 80 eV with an emission current of 2 mA.…”

Combined Experimental and Theoretical Study on the Formation of the Elusive 2-Methyl-1-silacycloprop-2-enylidene Molecule under Single Collision Conditions via Reactions of the Silylidyne Radical (SiH; X2Π) with Allene (H2CCCH2; X1A1) and D4-Allene (D2CCCD2; X1A1)

“…We further characterized the ro-vibrational energy distribution of the silylidyne radical in its ground electronic state (X 2 Π) employing laser-induced fluorescence (LIF) for the A 2 ∆ ← X 2 Π band. [82][83][84] Briefly, the beam of the detection laser propagated within the scattering plane and orthogonally intercepted the chopped section of the pulsed silylidyne radical beam. Fluorescence of electronically excited silylidyne via the A 2 ∆ ← Page 8 of 45…”