Knowledge Bank

It is shown that the peak positions of the 600 {\AA} bands of $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}He2$ (A $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma g+\to X1\Sigma g+$) can be derived from those of $\mathrm{<mrow\; data-mjx-texclass="ORD">4</mrow>}He2$ if the vibrational numbering adopted in a recent $determination1$ of the A state RKR potential curve is used. Given this A state potential and the 600 {\AA} band spectrum, we developed a least-squares iterative procedure to derive the repulsive X potential in the range 2.4 {\AA} ($1.05>V>$.02 eV). The result, V(R)=202 exp (--3.88 R) eV, compares favorably with curves derived from elastic scattering data and from theoretical calculations. $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$A.L. Smith and K. W. Chow, J. Chem. Phys. 52, 1010 (1970).