tailieunhanh - Chapter 10: Line profiles

Vạch quang phổ không phải là vô cùng hẹp, HỌ có chiều rộng hữu hạn. Một đồ thị của hoặc cường độ rạng rỡ trên mỗi đơn vị bước sóng (hoặc tần số) so với bước sóng (hoặc tần số) là hồ sơ cá nhân dòng. Có nhiều nguyên nhân MỘT SỐ Mở rộng đường, Một số nội bộ với nguyên tử, bên ngoài khác, và MỖI NÓ Tạo hồ sơ cá nhân đặc trưng. | 1 CHAPTER 10 LINE PROFILES Introduction. Spectrum lines are not infinitesimally narrow they have a finite width. A graph of radiance or intensity per unit wavelength or frequency versus wavelength or frequency is the line profile. There are several causes of line broadening some internal to the atom others external and each produces its characteristic profile. Some types of profile for example have a broad core and small wings others have a narrow core and extensive broad wings. Analysis of the exact shape of a line profile may give us information about the physical conditions such as temperature and pressure in a stellar atmosphere. Natural Broadening Radiation Damping The classical oscillator model of the atom was described in section . In this model the motion of the optical electron when subject to the varying electromagnetic field of a light wave obeys the differential equation for forced damped oscillatory motion 2 eE x ỵx ra0 x - cos rat. m Because the oscillating hence accelerating electron itself radiates the system loses energy which is equivalent to saying that the motion is damped and Y is the damping constant. Electromagnetic theory tell us that the rate of radiation of energy from an accelerating electron is 2 e2 x2 . 3 4 80c3 The reader as always should check the dimensions of this and all subsequent expressions. For an electron that is oscillating the average rate of loss of energy per cycle is 2 e2 x2 3 4 80c3 Here the bar denotes the average value over a cycle. 2 If the amplitude and angular frequency of the oscillation are a and o0 the maximum acceleration is a 0 and the mean square acceleration is -2-a2 44. The energy kinetic plus potential of the oscillating electron is W 1 ma 2 0- Thus we can write for the average rate of loss per cycle of energy from the system by electromagnetic radiation 2. e 2 2 3 W 3 4ne0mc The energy therefore falls off according to 1 2 2 W - 1- 3 W. 3 4ns0mc The .

• Vật lý
• khí qkhí quyển quyển sao
• vật lí nâng cao
• tài liệu vật lý
• kiến thức vật lý căn bản
• vật lí nâng cao
• trắc nghiệm lí thuyết vật lí uyển sao