Zeeman and Stark Effect

methods of spectroscopy

1. Dr. E. Sindhuja Assistant Professor ZEEMAN AND STARK EFFECT

2. Born May -- 25 , 1865, Zonnemaire , Neth . Died Oct. 9, 1943, Amsterdam, Dutch physicist who shared with  Hendrik A. Lorentz  the Nobel Prize for Physics in 1902 for his discovery of the Zeeman effect Zeeman, who had been a student of Lorentz at the University of  Leiden , began lecturing at Leiden in 1890. Pieter Zeeman

3. Six years later, at the suggestion of Lorentz, he investigated the effect of magnetic fields on a source of  light and found that each of the lines in the spectrum of emitted light split into several lines; this became known as the Zeeman effect.  The atomic energy levels, the transitions between these levels, and the associated spectral lines discussed to this point have implicitly assumed that there are no magnetic fields influencing the atom. If there are magnetic fields present, the atomic energy levels are split into a larger number of levels and the spectral lines are also split. This splitting is called the  Zeeman Effect . Zeeman Effect

4. Observation along the magnetic field vector corresponds to the longitudinal Zeeman effect and perpendicular to it to the transverse Zeeman effect, respectively. The normal Zeeman effect is characterized by a triplet or doublet splitting of the spectral line in case of transverse or longitudinal observation, respectively. The middle line in the triplets represents the component of the spectral line which is unaffected by the magnetic field, the other two lines shift by the same amount to higher and lower wavelengths, respectively, due to the applied field. Experimental Observation

5. Depending on the observation direction, the polarization of the split lines is different. In the longitudinal case, circular polarization occurs with opposite sense of rotation for the two components. Transversally, the middle component of the triplet is polarized parallel to the field and the other two perpendicular. For the anomalous Zeeman effect, the splitting is more complicated, even if the shift is still proportional and symmetrical to the applied field. Cont..,

6. Born April 15, 1874, Schickenhof , Ger . died June 21, 1957, Traunstein , W. Ger . German physicist who won the 1919  Nobel Prize for Physics for his discovery in 1913. Johannes Stark

7. An  electric field would cause splitting of the lines in the spectrum of light emitted by a luminous substance; the phenomenon is called the Stark effect Or The Stark effect is the electric analogue to the Zeeman effect, i.e., a particle carrying an electric dipole moment, like the H-atom, will get a splitting of its energy levels when subjected to an exterior electric field. As the splitting of a line of the helium spectrum shows, the splitting is not symmetric like that of the Zeeman effect. Stark Effect

8. The splitting of the energy levels by an electric field first requires that the field polarizes the atom and then interacts with the resulting electric dipole moment. That dipole moment depends upon the magnitude of M j , but not its sign, so that the energy levels show splitting proportional to quantum numbers J+1 or J+1/2, for integer and half-integer spins respectively. Earlier experimenters had failed to maintain a strong electric field in conventional spectroscopic light sources because of the high electrical conductivity of luminous gases or vapours. Stark observed the hydrogen spectrum emitted just behind the perforated cathode in a positive-ray tube. Stark Effect Experimental S tudy

9. With a second charged electrode parallel and close to this cathode, he was able to produce a strong electric field in a space of a few millimetres. At electric field intensities of 100,000 volts per centimetre, Stark observed with a spectroscope that the characteristic spectral lines, called  Balmer lines, of hydrogen were split into a number of symmetrically spaced components, some of which were linearly polarized (vibrating in one plane) with the electric vector parallel to the lines of force, the remainder being polarized perpendicular to the direction of the field except when viewed along the field. Cont..,

10. This transverse Stark effect resembles in some respects the transverse Zeeman effect, but, because of its complexity, the Stark effect has relatively less value in the analysis of complicated spectra or of atomic structure. Historically, the satisfactory explanation of the Stark effect (1916) was one of the great triumphs of early  quantum mechanics . Cont..,

11. Thank you