英汉,原子物理.doc

Quantum mechanics Historical introduction Beginning: In 1859， German physicist Gustav Kirchhoff (基尔霍夫) The path to quantum mechanics begins in 1859 with the work of the German physicist Gustav Kirchhoff. 背景：Maxwell hadn’t even begun to formulate（用公式表示、系统地阐述） his EM equations, statistical mechanics didn’t exist and thermodynamics was in its infancy（幼年）. In the continuous spectrum there appeared dark D-lines from the light emitted by the sun. D-lines came from the absorption of light from the interior of the sun by sodium（钠） atoms at its surface. (太阳连续的光谱，通过钠蒸气，就出了黑线，这黑线实际上是吸收光谱) Fig. P36 2-1 Kirchhoff imagined a container-a cavity（可以辐射和吸收EM. Within the cavity, there is a distribution of radiation of all wavelengths.） : The intensity（强度） distribution (a quantity that measures the rate at which energy falls on a unit area of surface) (辐射到单位面积的能量) : The intensity between the wavelength and : the emissivity.它表示从物体表面发出的波长在附近的单位波长间隔内的辐射功率。物体对波长在附近的电磁波的面辐射强度. : The rate at which radiation energy is emitted by a unit area of the wall in the interval from to is : the coefficient of absorption物体对波长在附近的辐射能量的吸收因数(百分比) : The rate at which radiation energy can be absorbed per unit area of the wall in the interval from to is On equilibrium， the rate of total emission from a wall is just balanced by the rate of absorption by the wall. where the integration are over all values of the wavelength. For each wavelength: To perfect absorber-blackbody, (若物体在任何温度下，对任何波长的辐射能的吸收比都等于1， 则称该物体为绝对黑体，简黑体) Then In fact, depends only on and T, The radiation inside the perfect absorbing body is blackbody radiation. The next step: In the mid-1880s, physicist Ludwig Boltzmann and J.Stefan 背景：Maxwell had formulated his equations; the radiation found in a blackbody is EM radiation which produces a pressure. : If the radiation in the blackbody had an energy density given by : a total energy density gotten by integrating over all wavelengths. Stefan-Boltzmann f