Paschen spectral series

Electron Energy Transitions This energy-state diagram for a hydrogen atom shows some of the energy transitions for the Lyman, Balmer, and Paschen spectral series. Bohr s model of the atom accounted mathematically for the energy of each of the transitions shown. 

On the experimental side came the discovery of other spectral series in hydrogen which beautifully fit Balmer s formula. 1908 - Paschen s series (m = 3) in the... 

Paschen series. One of the hydrogen spectral series in the infrared region. 

Figure 1. Diagram showing the electron jumps producing the spectral lines in the Balmer (visible) series, the Paschen (infrared) series, and the Lyman (ultraviolet) series.

In this relationship, m is an integer greater than 2, with each value of m representing a different spectral line. Balmer was able to predict the wavelength of some spectral lines that were in the near ultraviolet range. The success of Balmer s equation was strengthened when other spectral series of emission lines were discovered in the ultraviolet (Lyman series) and in the infrared (Paschen series). The lines in their series could be determined by modified Balmer equations ... 

The discovery of two other series of emission lines of hydrogen came later. They are named for their discoverers the Lyman series in the ultraviolet range and Paschen series in the infrared region. Although formulas were devised to calculate the spectral lines, the physics behind the math was not understood until Niels Bohr proposed his quantized atom. Suddenly, the emission spectrum of hydrogen made sense. Each line represented the energy released when an excited electron went from a higher quantum state to a lower one. 

The study of the hydrogen atom also played an important role in the development of quantum theory. The Lyman, Balmer, and Paschen series of spectral lines observed in incandescent atomic hydrogen were found to obey the empirical equation... 

Subsequent to the discovery of the Balmer series of lines in the visible region of the electromagnetic spectrum, it was found that many other spectral lines are also present in nonvisible regions of the electromagnetic spectrum. Hydrogen, for example, shows a series of spectral lines called the Lyman series in the ultraviolet region and still other series (the Paschen, Brackett, and Pfund series) in the infrared region. 

Bob looks at Miss Muxdroozol. Jumps that land on or come from the second orbit produce what is called the Balmer series, which correspond to spectral lines observable in optical spectra. The Lyman series correspond to more energetic changes and produces spectral lines in the ultraviolet. Paschen and higher order series produce low-energy infrared and even radio signals. He pronounces the last series PA-SHUN. 

Eventually, this series of lines became known as the Balmer series. Balmer wondered whether his little formula might be extended to study the spectra of other elements. He knew similar patterns exist in the line spectra of many elements. He also wondered about spectral lines that the human eye can t see. A few years later, in 1906, additional series of lines were in fact discovered for hydrogen in the ultraviolet region of the spectrum. These were called the Lyman series after their discoverer, Theodore Lyman. Other famous series are the Paschen series, named after German scientist Friedrich Paschen, the Brackett series, named after U.S. scientist F. S. Brackett, and the wonderful Pfund series, named after U.S. scientist August Herman Pfund. The Paschen, Brackett, and Pfund series lie in the infrared region. ... 

Each set of arrows in step 2 represents a spectral emission series. Label five of the series, from greatest energy change to least energy change, as the Lyman, Balmer, Paschen, Brackett, and Pfund series. 

Other series of spectral lines occur in the ultraviolet (Lyman series) and infrared (Paschen, Brackett and Pfund series). All... 

Aware of only these four hues, Balmer calculated 1 for a fifth hue lyn = 7). A hue with a wavelength very close to the predicted value was observed experimentally. Balmer suggested that his formula might also predict wavelengths of other series of spectral fines by using integer values for n other than 2 and rw n L 1. Other series of hydrogen lines were not known then, but were subsequently discovered (the Lyman, Paschen, Brackett, and Pfund series of fines). 

What electron transitions account for the Balmer series Hydrogen s emission spectrum comprises three series of lines. Some wavelengths are ultraviolet (Lyman series) and infrared (Paschen series). Visible wavelengths comprise the Balmer series. The Bohr atomic model attributes these spectral lines to transitions from higher-energy states with electron orbits in which n = n, to lower-energy states with smaller electron orbits in which n = nf. 

Extend the Bohr model by calculating the wavelength and energy per quantum for the electron orbit transition for which nf= 3 and n, = 5. This transition accounts for a spectral line in hydrogen s Paschen series. 

For the Balmer series, nf is simply 2 and n, takes the values 3, 4, 5, or 6. In 1908 the German physicist Friedrich Paschen (1865-1947) discovered new spectral lines fitting the above equation if nf = 3 and n = 4 and n, = 5. In 1906, Harvard physicist Theodore Lyman (1874-1954) discovered an ultraviolet series of spectral lines from hydrogen corresponding to nf = 1 and some 16 years later infrared spectral lines were discovered corresponding to nf = 4 and nf = 5. 

Other series of spectral lines occur in the ultraviolet (Lyman series) and infrared (Paschen, Brackett and Pfund series). All lines in all the series obey the general expression given in equation 1.5 where n > n. For the Lyman series, n=, for the Balmer series, n = 2, and for the Paschen, Brackett and Pfund series, k = 3, 4 and 5 respectively. Figure 1.3 shows some of the allowed transitions of the Lyman and Balmer series in the emission spectrum of atomic H. Note the use of the word allowed, the transitions must obey selection... 

The first set of transitions shown in Figure 14.15, in which the lower-energy state ( 2 state) is the n = 1 state, corresponds to the series of spectral hnes in the ultraviolet that is known as the Lyman series. The second set of transitions, in which ri2 = 2, is the Balmer series. The first four lines of the Balmer series are in the visible region and the others are in the ultraviolet. The next series, in which 2 = 3, is the Paschen series. It lies in the infrared. It is not shown in the figure. 

In a magnetic field strong enough to make the split components of adjacent multiplets overlap, we have what is known as the Paschen-Back effect. 2 Once again L and S are uncoupled and the spectral splitting pattern tends toward series of triplets as for the normal Zeeman case with each triplet component itself showing the field-free multiplicity of the transition. 

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