ASTR Spring 2008 Joel E. Tohline, Alumni Professor 247 Nicholson Hall [Slides from Lecture20]
Light and Atomic Transitions Electron orbital transitions upward –Absorption of a photon (of appropriate energy, frequency, wavelength) –Collisional excitation ( rate and effectiveness of collisions depends on density and temperature of gas ) –Ionization possible
Wavelength and Frequency Wavelength = Frequency = c = speed of light = c
Light and Atomic Transitions Electron orbital transitions downward –Spontaneous Emission of a photon (of appropriate energy, frequency, wavelength) –Collisional de-excitation ( rate and effectiveness of collisions depends on density and temperature of gas ) –Recombination is opposite of ionization –Stimulated emission also possible
Light and Atomic Transitions Electron orbital transitions upward –Absorption of a photon (of appropriate energy, frequency, wavelength) –Collisional excitation ( rate and effectiveness of collisions depends on density and temperature of gas ) –Ionization possible
Light and Atomic Transitions Electron orbital transitions downward –Spontaneous Emission of a photon (of appropriate energy, frequency, wavelength) –Collisional de-excitation ( rate and effectiveness of collisions depends on density and temperature of gas ) –Recombination is opposite of ionization –Stimulated emission also possible
Light and Atomic Transitions Electron orbital transitions upward –Absorption of a photon (of appropriate energy, frequency, wavelength) –Collisional excitation ( rate and effectiveness of collisions depends on density and temperature of gas ) –Ionization possible
Light and Atomic Transitions Electron orbital transitions downward –Spontaneous Emission of a photon (of appropriate energy, frequency, wavelength) –Collisional de-excitation ( rate and effectiveness of collisions depends on density and temperature of gas ) –Recombination is opposite of ionization –Stimulated emission also possible
Light and Atomic Transitions Electron orbital transitions downward –Spontaneous Emission of a photon (of appropriate energy, frequency, wavelength) –Collisional de-excitation ( rate and effectiveness of collisions depends on density and temperature of gas ) –Recombination is opposite of ionization –Stimulated emission also possible
Light and Atomic Transitions Electron orbital transitions upward –Absorption of a photon (of appropriate energy, frequency, wavelength) –Collisional excitation ( rate and effectiveness of collisions depends on density and temperature of gas ) –Ionization possible
Light and Atomic Transitions Electron orbital transitions downward –Spontaneous Emission of a photon (of appropriate energy, frequency, wavelength) –Collisional de-excitation ( rate and effectiveness of collisions depends on density and temperature of gas ) –Recombination is opposite of ionization –Stimulated emission also possible
Kirchhoff’s Laws Hot dense gas produces a continuous spectrum ( a complete rainbow of colors ) Hot transparent gas produces an emission line spectrum Cool transparent gas in front of a source of continuous spectrum produces an absorption line spectrum.
Kirchhoff’s Laws Hot dense gas produces a continuous spectrum ( a complete rainbow of colors ) Hot transparent gas produces an emission line spectrum Cool transparent gas in front of a source of continuous spectrum produces an absorption line spectrum.
Kirchhoff’s Laws Hot dense gas produces a continuous spectrum ( a complete rainbow of colors ) Hot transparent gas produces an emission line spectrum Cool transparent gas in front of a source of continuous spectrum produces an absorption line spectrum.
Kirchhoff’s Laws Hot dense gas produces a continuous spectrum ( a complete rainbow of colors ) Hot transparent gas produces an emission line spectrum Cool transparent gas in front of a source of continuous spectrum produces an absorption line spectrum.