Raman effect data for rutile are evaluated for the force constants. It is shown that quasi-molecules TiO2 are formed with strong Ti–O bonds although every Ti atom is surrounded by 6 O atoms in about equal distances. The main force constants are (in 105 dynes/cm) 1.7 for the Ti–O bond of the quasi-molecules, 0.06 for the other Ti–O bonds, 0.2 for O–O bonds. The spectrum can be interpreted as that of coupled modified TiO2 molecules whose effective bond strength is a combination of the actual bond strengths.

Frequency formulas for some atomic groups occurring in silicates (Si2O7, Si3O9 ring, SiO3 chain, SiO2 network) are computed, using simplified force systems, and force constants are calculated. The strong force between the O atoms connecting the SiO4 groups of the Si3O9 ring is especially remarkable. Further observations are necessary to indicate the choice of less simple force systems.

Electric fields in the form of square or rectangular waves, saw-tooth waves, and exponential waves were applied to an electroluminescent phosphor. The light output contained green and blue luminescence bands, which were examined separately by means of filters, a photomultiplier, and an oscilloscope. Square wave fields produce luminescence peaks whenever the field is changing, followed by a decline in luminescence when the field is steady. Peak heights increase proportionally to about the fourth power of the field strength. They decrease with increasing frequency for the green band, while for the blue band they first increase up to about 2000 cps and then decrease. The decay obeys power laws with different exponents before and after a critical time of about 0.7 msee. A rectangular field pulse of greater duration than the critical time produces, in the green band, peaks of equal total intensity at the field reversals; in the blue band, the same excitation produces peaks with equal changes in intensity. Other field shapes produce peaks of luminescence whose heights and shapes depend on field shape and duration of the steady field before it is changed. Additional peaks in the green band appear whenever the field begins to decrease.Observations are interpreted by using the following assumptions: excitation is due to collision processes of accelerated electrons; green luminescence involves transitions to the conduction band and to traps; blue luminescence is caused by transitions within a luminescence center; the effective field changes in time because o[ the development of polarization charges. Additional peaks in the green band are due to recombination processes of the polarization charges. EQUIPMENT AND PROCEDUREThe fields were produced by using generators giving a variety of signal wave shapes. The genera-

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