Hyperfine Spectra of 7Li35Cl and 7Li37Cl

Using a newly constructed electric resonance molecular beam apparatus the hyperfine spectra of ⁷Li³⁵Cl and ⁷Li³⁷Cl have been measured. At present the most distinctive feature of the apparatus is its 2$\frac{1}{2}$ ‐m‐long C region, allowing linewidths of 300 Hz in this experiment. Some of the details of the design and operation of the apparatus are presented. The spectra were measured in zero magnetic and low electric fields with the results listed below. Lithium chloride hyperfine constants in kilohertz $$\begin{array}{ccccc}{}^7{\mathrm{Li}}^{35}\mathrm{Cl}& \text{ν =0}& \text{ν=1}& \text{ν=2}& \text{ν=3}\\ {\mathrm{eqQ}}_{\mathrm{Cl}}& \text{−3059.51(15)}& \text{−3442.1(9)}& \text{−3808(7)}& \text{−4175(7)}\\ {\mathrm{eqQ}}_{\mathrm{Li}}& \text{249.93(50)}& \text{244.6(20)}& \text{237(10)}& \text{225(10)}\\ c_{\mathrm{Cl}}& \text{1.946(20)}& \text{1.98(7)}& & \\ c_{\mathrm{Li}}& \text{0.956(3)}& \text{0.92(9)}& & \\ c_3& \text{0.511(20)}& \text{0.55(6)}& & \\ c_4& \text{0.025(20)}& \text{0.03(6)}& & \\ {}^7{\mathrm{Li}}^{37}\mathrm{Cl}& & & & \\ {\mathrm{eqQ}}_{\mathrm{Cl}}& \text{−2410.9(6)}& \text{−2711(7)}& & \\ {\mathrm{eqQ}}_{\mathrm{Li}}& \text{250.0(10)}& \text{250(10)}& & \\ c_{\mathrm{Cl}}& \text{1.66(5)}& & & \\ c_{\mathrm{Li}}& \text{1.03(6)}& & & \\ c_3& \text{0.42(4)}& & & \\ c_4& \text{0.02(3)}& & & \end{array}$$