Flory M A, McLamarrah S K, Ziurys L M
Department of Chemistry, Steward Observatory, University of Arizona, Tucson, Arizona 85721, USA.
J Chem Phys. 2006 Nov 21;125(19):194304. doi: 10.1063/1.2355495.
The pure rotational spectrum of the ZnF radical has been recorded in the range of 176-527 GHz using millimeter/submillimeter direct absorption techniques. This study is the first gas-phase spectroscopic investigation of this species. Between 5 and 11 transitions were measured for each of five isotopologues of this radical (64ZnF, 66ZnF, 67ZnF, 68ZnF, and 70ZnF) in the ground and several excited vibrational (v=1, 2, and 3) states. Each transition consists of spin-rotation doublets with a splitting of approximately 150 MHz, indicating that the electronic ground state of ZnF is 2Sigma+, as predicted by theory. Fluorine hyperfine splitting was observed in three isotopologues (64ZnF, 66ZnF, and 67ZnF), and hyperfine structure from the zinc-67 nucleus (I=52) was additionally resolved in 67ZnF. Rotational, fine structure, and 19F and 67Zn hyperfine constants were determined for ZnF, as well as equilibrium parameters. The bond length of the main isotopologue 64ZnF was calculated to be re=1.7677 A. Evaluation of the hyperfine constants indicates that the sigma orbital containing the unpaired electron is approximately 80% 4s(Zn) in character with approximately 10% contributions from each of the 2p(F) and 4p(Zn) orbitals. These results imply that ZnF is somewhat less ionic than CaF, as suggested by theory.
利用毫米/亚毫米直接吸收技术，在176 - 527 GHz范围内记录了ZnF自由基的纯转动光谱。本研究是对该物种的首次气相光谱研究。对该自由基的五种同位素变体（64ZnF、66ZnF、67ZnF、68ZnF和70ZnF）在基态以及几个激发振动态（v = 1、2和3）下，分别测量了5至11条跃迁谱线。每条跃迁谱线由自旋 - 转动双重态组成，分裂约为150 MHz，这表明ZnF的电子基态为2Σ⁺，正如理论所预测的那样。在三种同位素变体（64ZnF、66ZnF和67ZnF）中观察到了氟超精细分裂，并且在67ZnF中还分辨出了来自锌 - 67核（I = 5/2）的超精细结构。确定了ZnF的转动、精细结构以及19F和67Zn的超精细常数，还有平衡参数。主要同位素变体64ZnF的键长经计算为re = 1.7677 Å。对超精细常数的评估表明，包含未成对电子的σ轨道约80%具有4s(Zn)特征，2p(F)和4p(Zn)轨道各贡献约10%。这些结果表明，正如理论所暗示的，ZnF的离子性略低于CaF。
