Presents a method for determining crystal field splitting patterns within the ionic model without the use of formal group theory.

Diatomics-in-molecules theory applied to the Li3 molecule leads to the prediction of two forms stable with respect to Li2(1Σg+) + Li(2S) : a bent 2A1 state with an atomization energy at 0°K of 32.74 kcal/mole and an ionization energy of about 111 kcal/mole; a strongly bent 2B2 state with an atomization energy at 0°K of 30.34 kcal/mole. Potential-energy surfaces and fundamental vibrational frequencies are predicted for both states. Characteristics of the less stable linear conformation are discussed and compared with H3.

Presents a design for a simple and inexpensive student spectroscope.

A mass scale freshman laboratory experimentHollenberg's recent suggestion1 on measurement of the Balmer lines of atomic hydrogen with a Beckman DU Spectrophotometer prompts us to describe our similar experiences in large freshman classes with the inexpensive student-built spectroscope described previou~ly.~ The Model 2 spectroscope, when calibrated with a low intensity mercury Pluecker tube, despite the error in the assumption of linear calibration,* is capable of two to three figure accuracy in measurement of the wavelengths of the three lowest energy Balmer lines in the visible emanation of a low pressure H, Pluecker tube. For example, two typical student results are 6530,4890,4330 A and 6550,4850,4350 A, as compared to literature values 6563,4861,4320 A.Two approaches, both originated by students, are recommended for evaluating the Rydberg constant R without prior knowledge of the quantum numbers involved in the electronic transitions. In the first, students derive from the Rydberg relation: l / A = R[l/aal/ne] the following equality involving their measured wavelengths X i : Al[l/az -1/nt2] = Xz[l/aal/n?I = As[l/a2 -I/ns21and, under the assumption of constant lower quantum number a, attempt to find pairs of integers (with ni > a)

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