Burton M A, Sheridan P M, Ziurys L M
Department of Chemistry and Biochemistry, University of Arizona, 1305 E 4th Street, Tucson, Arizona 85719, USA.
Department of Chemistry and Biochemistry, Canisius College, 2001 Main St., Buffalo, New York 14208, USA.
J Chem Phys. 2022 Nov 14;157(18):184307. doi: 10.1063/5.0118939.
The millimeter/submillimeter-wave spectrum of the SiP radical (XΠ) has been recorded using direct absorption spectroscopy in the frequency range of 151-532 GHz. SiP was synthesized in an AC discharge from the reaction of SiH and gas-phase phosphorus, in argon carrier gas. Both spin-orbit ladders were observed. Fifteen rotational transitions were measured originating in the Ω = 3/2 ladder, and twelve in the Ω = 1/2 substate, each exhibiting lambda doubling and, at lower frequencies, hyperfine interactions from the phosphorus nuclear spin of I = 1/2. The lambda-doublets in the Ω = 1/2 levels appeared to be perturbed at higher J, with the f component deviating from the predicted pattern, likely due to interactions with the nearby excited AΣ electronic state, where ΔE ∼ 430 cm. The data were analyzed using a Hund's case a Hamiltonian and rotational, spin-orbit, lambda-doubling, and hyperfine parameters were determined. A Π/Σ deperturbation analysis was also performed, considering spin-orbit, spin-electronic, and L-uncoupling interactions. Although SiP is clearly not a hydride, the deperturbed parameters derived suggest that the pure precession hypothesis may be useful in assessing the Π/Σ interaction. Interpretation of the Fermi contact term, b, the spin-dipolar constant, c, and the nuclear spin-orbital parameter, a, indicates that the orbital of the unpaired electron is chiefly p in character. The bond length in the v = 0 level was found to be r = 2.076 Å, suggestive of a double bond between the silicon and phosphorus atoms.
利用直接吸收光谱法在151-532千兆赫频率范围内记录了SiP自由基（XΠ）的毫米波/亚毫米波光谱。SiP是在氩载气中，通过SiH与气相磷反应的交流放电合成的。观察到了两个自旋轨道能级。测量了来自Ω = 3/2能级的15个转动跃迁，以及来自Ω = 1/2亚态的12个转动跃迁，每个跃迁都表现出λ双重分裂，并且在较低频率下，还表现出来自I = 1/2的磷核自旋的超精细相互作用。Ω = 1/2能级中的λ双重分裂在较高的J值时似乎受到了扰动，f分量偏离了预测模式，这可能是由于与附近激发的AΣ电子态相互作用所致，其中ΔE ∼ 430厘米⁻¹。使用洪德a型哈密顿量对数据进行了分析，并确定了转动、自旋轨道、λ双重分裂和超精细参数。还进行了Π/Σ去微扰分析，考虑了自旋轨道、自旋电子和L解耦相互作用。尽管SiP显然不是氢化物，但导出的去微扰参数表明，纯进动假说可能有助于评估Π/Σ相互作用。对费米接触项b、自旋偶极常数c和核自旋轨道参数a的解释表明，未配对电子的轨道主要具有p特征。发现v = 0能级的键长为r = 2.076 Å，表明硅和磷原子之间存在双键。
