Atomic spectral line splitting

G. E. Uhlenbeck and S. Goudsmit (1925) explained the splitting of atomic spectral lines by postulating that the electron possesses an intrinsic angular momentum, which is called spin. The component of the spin angular momen-... 

The need for improved background correction performance has generated considerable interest in applying the Zeeman effect, where the atomic spectral line is split into several polarised components by the application of a magnetic field. With a Zeeman effect instrument background correction is performed at, or very close to, the analyte wavelength without the need for auxiliary light sources. An additional benefit is that double-beam operation is achieved with a very simple optical system. 

Other types of background correction have also been developed. The Zeeman effect background correction system started gaining popularity in the early 1980s. An atomic spectral line when generated in the presence of a strong magnetic field can be split into a number of components... 

The last quantum number was proposed to solve a mystery. Emission spectroscopy measures the wavelengths of the electromagnetic radiation emitted when an electron in an atom drops from a higher-energy state to a lower one. Spectroscopists noticed that some spectral lines split into two lines when theory predicted that only one should exist. A new quantum property and number were needed to explain spectral splitting. At the time, the electron was considered a particle, and scientists called this new property spin, usually designated as ms. The spin quantum number can have only two possible values, +1/2 or -1/2. It is usually depicted as an arrow pointing either up or down. 

Zeeman AAS makes use of the splitting of the atomic spectral lines into several components under the influence of a magnetic field. When a magnetic field B (up to 10 kG) is applied, the shift in wavenumber (A Tm) of the so-called cr-components with respect to the original wavelength, where the 71-components may remain, is given by ... 

To compensate for the above effects background correction systems are introduced such as the use of Zeeman effect. Zeeman AAS uses splitting of atomic spectral lines... 

Stark effect The splitting of atomic spectral lines because of the presence of an external electric field. This phenomenon was discovered by the German physicist Johannes Stark (1874-1957) in 1913. 

Zeeman effect /zay-mahn/ The splitting of atomic spectral lines by an external applied magnetic field. It was first reported by the Dutch physicist Pieter Zeeman (1865-1943) m 1896. 

In 1896, Zeeman observed that application of an external magnetic field caused a splitting of atomic spectral lines. We shall consider this Zeeman effect for the hydrogen atom. We begin by reviewing magnetism. 

Zeeman effect The splitting of atomic spectral lines by a magnetic field. This effect was found by the Dutch physicist Pieter Zeeman (1865-1943) in 1896. Some of the patterns of line splitting that be explained both by classical electron theory and the BOHR THEORY of electrons in atoms. The Zeeman splitting that can be explained in these ways is known as the normal Zeeman effect. There exist more complicated Zeeman splitting patterns that cannot be explained either by classical electron theory or the Bohr theory. This more complicated type of Zeeman effect is known as the anomalous Zeeman effect. It was subsequently realized that the anomalous Zeeman effect occurs because of electron spin and that the normal Zeeman effect occurs only for transitions between singlet states. 

Acmally, other experimental evidence, such as splitting of atomic spectral lines due to applied magnetic fields, was also available. Furthermore, experience with the quantum theory of orbital angular momentum played a role in the treatment of electron spin. The reader should not think that the historical development of quantum theory of spin was as naive or simple as we make it appear here. 

A linear relation, which I call the fundamental relation of atomic spectroscopy, originating from the empirical atomic spectroscopy of the free hydrogen atom, lies at the heart of nonrelativistic quantum theory. This relation, which neglects the hyperfine interactions in the H-atom, which leads to the so-called hyperfine splitting of the individual atomic spectral lines, can be stated as follows ... 

This splitting of the energy levels by the magnetic field leads to the splitting of the lines in the atomic spectrum. The wave number v of the spectral line corresponding to a transition between the state /i mi) and the state nihm2) is... 

Transitions between states are subject to certain restrictions called selection rules. The conservation of angular momentum and the parity of the spherical harmonics limit transitions for hydrogen-like atoms to those for which A/ = 1 and for which Am = 0, 1. Thus, an observed spectral line vq in the absence of the magnetic field, given by equation (6.83), is split into three lines with wave numbers vq + (/ bB/he), vq, and vq — (HbB/he). 

Zeeman effect spect A splitting of spectral lines in the radiation emitted by atoms or molecules In a static magnetic field. za man i.fekt)... 

We wish to point out, that by use of a suitable fiber which further broadens the spectrum, this fs laser frequency measurement technique has now been simplified to a setup with a single laser, as described elsewhere in this volume [6]. With the technique of Fig. 6, the 15 — 25 transition frequency was measured twice, first with a GPS referenced commercial Cs clock [29], and second with a transportable Cs atomic fountain clock constructed by A. Clairon and coworkers in Paris [30]. A total of 614 spectral lines was recorded in the latter measurement during ten days, and fitted with the described line shape model [13]. After adding a correction of 310 712 233(13) Hz to account for the hyperfine splitting of the 15 and 25 levels, we obtain for the hyperfine centroid [28] ... 

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