| 释义 |
photon1 Physics.|ˈfəʊtɒn|
[f. photo- 1 + -on1.
In senses 1 and 2 the ending -on may be merely arbitrary.]
†1. = troland. Obs.
1916L. T. Troland in Trans. Illuminating Engin. Soc. (U.S.) XI. 950, I have..found it very convenient to express all intensity measures in terms of a unit of retinal illumination which I have called the photon. 1929Bureau of Standards Jrnl. Res. (U.S.) II. 445 If the rods initiate the nerve activity responsible for the blue arcs a pure spectral stimulus of wave length, say, 640 mµ, would have to be at a much higher illumination (measured in photons..) than a stimulus of wave length less than, say 550 mµ. 1934Jrnl. Gen. Physiol. XVII. 241 With the present apparatus, which has a pupil area of 2·54 sq. mm. the maximal retinal illumination available in the central test area when it is not interrupted is very nearly 6000 photons. 1944[see troland]. 1949J. H. Prince Visual Devel. I. vi. 85 Feldman..has estimated that, whereas a rod requires only 0·00025 photons to stimulate it, a cone requires 0·025 photons. 1953H. H. Emsley Visual Optics (ed. 5) II. xviii. 232 A surface of luminance one millilambert observed through a 4 mm. diameter pupil gives a retinal illumination of 2·5 × 42 = 40 photons.
†2. (See quot.) Obs. rare.
1921J. Joly in Proc. R. Soc. B. XCII. 226 In the foregoing pages.. the unit light stimulus discharged by a single visual fibre is frequently referred to. It represents a very small amount of energy... It must not be confused with the quantum of energy... I propose to designate it a photon. Ibid. 228 The stimulus value of the three colour sensations in such proportions as to give white light is nine photons.
3. A quantum of light or other electro-magnetic radiation, the energy of which is proportional to the frequency of the radiation.
1926G. N. Lewis in Nature 18 Dec. 874/1, I therefore take the liberty of proposing for this hypothetical new atom, which is not light but plays an essential part in every process of radiation, the name photon. 1929Jrnl. Amer. Chem. Soc. LI. 2850 In 1906, Einstein showed that the photo-electric effect and many photochemical reactions could be explained in terms of the Quantum Theory if light itself consisted of discrete particles of energy or quanta, now usually called photons. 1934Discovery May 125/1 Photons (quanta or packets of electro-magnetic energy) are in general more efficient in bringing about atomic changes than particles of corresponding energy. 1942J. D. Stranathan ‘Particles’ of Mod. Physics viii. 357 The ejection of a β particle might leave the new nucleus in an excited state. In this case one would expect the disintegration to be followed by the radiation of a γ-ray photon having an energy equal to the excitation energy. 1948Sci. News VI. 75 In the quantum theory a light signal cannot be sub-divided indefinitely, but consists of finite units, so-called light quanta, or ‘photons’, each carrying an amount of energy proportional to the frequency of the light wave of which they form part. 1959[see Compton]. 1968M. S. Livingston Particle Physics v. 96 In particle physics, the individual photons entering or emerging from interactions are treated as particles with zero rest mass, velocity c, energy E = hv, and momentum p = E/c. 1971Nature 2 July 67/2 The dark-adapted human eye is capable of detecting a pulse of less than a hundred photons. 1977Dædalus Summer 26 On the subnuclear level the gluons are the analogues of the photons or quanta of the electromagnetic field for atomic processes.
4. Special Comb.: photon rocket, a rocket propelled by the backward ejection of photons.
1949Jrnl. Brit. Interplanetary Soc. VIII. 242 Two possible schemes for ultilizing nuclear energy are then considered, the first using a nuclear ‘boiler’ to heat a working fluid which is then expanded through a nozzle in the normal way and the second using the energy direct in a ‘photon’ rocket. 1958C. C. Adams et al. Space Flight 347 Others ponder photon rockets driven by parallel beams formed by properly designed reflectors.
Hence phoˈtonic a.
1938R. W. Lawson tr. Hevesy & Paneth's Man. Radioactivity (ed. 2) v. 61 In the production of the former the whole of the energy of the γ-quantum or photon..is transmitted to the electron, whereas in the production of recoil electrons only a fraction of the photonic energy is handed over to the recoil electron. 1952R. E. Marshak Meson Physics iii. 98 The first observations on the photonic production of charged π mesons were made in 1949. 1952Jrnl. Brit. Interplanetary Soc. XI. 59 Whether the ‘jet propulsion engine’ concerned is of a type that consumes air, burns chemical propellants, utilizes nuclear power, or represents some form of electronic or photonic drive. 1958C. C. Adams et al. Space Flight 348 The best we can do is to base our calculations on highly developed systems using atomic, ionic, or photonic particles. 1969Auden City without Walls 97 His light is felt as a friendly presence not a photonic bombardment. 1970Science 30 Jan. 618/2 The rocks were analyzed by photonic microscopy (transmitted and reflected light). |