. The Bell System technical journal . t for the scattering with shift-of-frequencyof light of the visible and adjacent ranges of the spectrum, as in the X-ray region theeffect was earlier discovered. CONTEMPORARY ADVANCES IN PHYSICS 75 turn with altered frequency are evidently relatively rare; otherwisethey could not have escaped the notice of those who have studiedgases.^^ Even scattering without change of frequency is unusual, un-less the primary light coincides exactly with a spectrum-line of themolecule; the blue of the sky is conspicuous only because the air is sothick; in the laboratory,
. The Bell System technical journal . t for the scattering with shift-of-frequencyof light of the visible and adjacent ranges of the spectrum, as in the X-ray region theeffect was earlier discovered. CONTEMPORARY ADVANCES IN PHYSICS 75 turn with altered frequency are evidently relatively rare; otherwisethey could not have escaped the notice of those who have studiedgases.^^ Even scattering without change of frequency is unusual, un-less the primary light coincides exactly with a spectrum-line of themolecule; the blue of the sky is conspicuous only because the air is sothick; in the laboratory, light scattered with unshifted wave-length bya gas can be seen only if the gas is dense, the primary light blindinglybrilliant, and the eye thoroughly rested. But if it had occurred to any physicist to seek for the effect with (say)mercury atoms, by crowding the atoms together into the liquid form,he would certainly have rejected the idea the moment after it flashedacross his mind; indeed it would probably never have flashed; for as. Fig, 1-—Sketch of scheme for observing fluorescence and scattering.(After Pringsheim.) soon as atoms are forced into such close proximity, their excited states,or those at least with which we are now concerned, simply free mercury atom, for instance, has a excited state—that is to say, a stationary state into which it will pass over, if beinginitially in its normal state it receives an acceptable offer of equiv-alent volts of energy. Were we to bombard mercury vapor with 6-voltquanta— with corpuscles of light, each possessing 6 equivalentvolts of energy—we might expect some of these to transfer equiva-lent volts to atoms which they strike, and rebound as there is no reason to expect anything of the sort with liquidmercury; there is no reason to suppose that the atoms are avid tograsp this particular amount of energy, and plenty of reason to supposethat they are not. The same holds for
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
