光电子的英文

IntroductionWhen a metallic surface is exposed to electromagnetic radiation above a certain threshold frequency, the light is absorbed and electrons are emitted. In 1902, Philipp Eduard Anton von Lenard observed that the energy of the emitted electrons increased with the frequency, or colour, of the light. This was at odds with James Clerk Maxwell's wave theory of light, which predicted that the energy would be proportional to the intensity of the radiation. In 1905, Einstein solved this paradox by describing light as composed of discrete quanta, now called photons, rather than continuous waves. Based upon Max Planck's theory of black-body radiation, Einstein theorized that the energy in each quantum of light was equal to the frequency multiplied by a constant, later called Planck's constant. A photon above a threshold frequency has the required energy to eject a single electron, creating the observed effect. This discovery lead to the quantum revolution in physics and earned Einstein the Nobel Prize in 1921. ExplanationThe photons of the light beam have a characteristic energy determined by the frequency of the light. In the photoemission process, if an electron absorbs the energy of one photon and has more energy than the work function, it is ejected from the material. If the photon energy is too low, the electron is unable to escape the surface of the material. Increasing the intensity of the light beam does not change the energy of the constituent photons, only the number of photons. Thus the energy of the emitted electrons does not depend on the intensity of the incoming light, but only on the energy of the individual photons.Electrons can absorb energy from photons when irradiated, but they follow an "all or nothing" principle. All of the energy from one photon must be absorbed and used to liberate one electron from atomic binding, or the energy is re-emitted. If the photon energy is absorbed, some of the energy liberates the electron from the atom, and the rest contributes to the electron's kinetic energy as a free particle.Laws of photoelectric emissionFor a given metal and frequency of incident radiation, the rate at which photoelectrons are ejected is directly proportional to the intensity of the incident light. For a given metal, there exists a certain minimum frequency of incident radiation below which no photoelectrons can be emitted. This frequency is called the threshold frequency. Above the threshold frequency, the maximum kinetic energy of the emitted photoelectron is independent of the intensity of the incident light but depends on the frequency of the incident light. The time lag between the incidence of radiation and the emission of a photoelectron is very small, less than 10-9 second.

电子的英语是electron。

electron

音标：英 [ɪˈlektrɒn]    美 [ɪˈlektrɑːn]

n.     电子

短语搭配：

例句：

1、Under certain conditions, electrons can behave like waves rather than particles.

在一定条件下，电子可以作波状运动，而不是粒子状运动

2、Protons are nearly 2000 times as heavy as electrons.

质子的质量几乎是电子的2,000倍。

3、The behavior of these unbound electrons is critical.

这些自由的电子作用极为重要。

电子的英语:electron

词语分析：

英 [ɪˈlektrɒn]

n.电子

短语：

例句：

1. The electron microscope uses a beam of electrons to produce images at high magnifications.

电子显微镜利用电子束形成高倍影像。

2. a scanning electron microscope

扫描电子显微镜

3. when an electron drops from an excited state to a less excited state

当电子从激发态降到较弱的激发态时