No abstract

Eighteen bands of the A G = +4, +3 and -2 sequences of the B 'Z+-X 'Z+ system of AI0 have been photographed at high resolution and analysed for the rotational structure. It has been found that the spin-doubling constant y in the X 2 Z + state increases very rapidly with the vibrational quantum number U, while in the B state it remains almost constant and does not change with U. Also, the spin doubling in the u"=4, 5, 6 and 7 levels of the X 'Z+ state is not simply a linear function of N as found by earlier workers.It is found necessary to include a cubic term in N in the formula for the observed spin doubling in the X 'Z+ state. The unusual increase in the spin doubling is attributed to the proximity and the interactions of the vibrational levels of the A 'II, state with the vibrational levels of the X 'Z+ state.

The E2Δi–A2Πi transition of AlO in the ultraviolet region has been excited in a high frequency discharge through a flowing mixture of AlCl3 vapour, argon, and oxygen and photographed at high resolution. The 0–0 and 0–1 bands of this transition at 2500.1 and 2545.9 Å respectively have been analysed for the rotational structure. Rotational perturbations and predissociation have been observed in the E2Δi state. Λ-doubling has been observed in both the bands for the transition E2Δ3/2–A2Π1/2. A weak rotational perturbation has been detected in the ν = 1 level of the A2Π3/2 state. In the same spectral region the 1–1, 2–2, 3–3 bands (observed for the first time) and the 1–2 band of the D2Σ+–X2Σ+ system have also been recorded and analysed for their rotational structure.

Several bands of the C2Πr – X2Σ+transition of AlO in the region 2800–3400 Å have been photographed at high resolution. A unique and unambiguous analysis of the rotational structure has been done for the first time for the 2–0, 1–0, 2–1, 0–0, 1–1, 0–1, 1–2, and 0–2 bands of this system. Fairly accurate rotational constants Beff and Deff have been determined for the ν = 2, 1, and 0 levels of the C2Πr state. Severe rotational perturbations have been observed in the C2Π, state.Equilibrium rotational constants (in cm−1) of the C2Π, state are Be ≈ 0.6049 and αe ≈ 0.0046.

The A2Π–X2Σ+ system of MgCl has been photographed at high resolution and analyzed for the rotational structure. Analysis of the low-frequency sub-bands of the 0–0, 0–1, and 0–2 bands showed that there is a nonzero Λ doubling in the common vibrational level ν′ = 0, thereby indicating that the A2Π state is regular and not inverted as presumed by earlier workers. Spin-doubling has been seen in the ν = 1 and 2 levels of the X2Σ+ state. Rotational analysis of the high-frequency sub-band has also been done for the 0–0 band.