Spectroscopic notation
Encyclopedia
Spectroscopic notation provides various ways to specify atomic ionization states
, as well as atomic
and molecular orbitals.
by the element's symbol followed by a Roman numeral. The numeral I is used for spectral lines associated with the neutral element, II for those from the first ionization state, III for those from the second ionization state, and so on. For example, 'He I' denotes lines of neutral helium
, and 'C IV' denotes lines arising from the third ionization state, C+++, of carbon
.
, l. The letters, "s", "p", "d", and "f", for the first four values of l were chosen to be the first letters of properties of the spectral series observed in alkali metals. Letters for subsequent values of l were assigned in alphabetical order, omitting the letter "j":
This notation is used to specify electron configurations and to create the term symbol
for the electron
states in a multi-electron atom. When writing a term symbol, the above scheme for a single electron's orbital quantum number
is applied to the total orbital angular momentum associated to an electron state.
phrase for remembering the sequence S. P. D. F. G. H. ... is "Sober Physicists Don't Find Giraffes Hiding In Kitchens Like Mine". One is expected to remember that after the F, the letters in the sequence are alphabetical (excluding J).
There are a few other mnemonic
phrases for remembering the sequence, for example:
Another mnemonic is: if you don't memorize the proper order, you will get a SPeeDy F!
The quantum number that represents this momentum is the Λ.
Λ=0,1,2,3,...
Symbols: Σ,Π,Δ,Φ
For Σ states, one denotes if there is a reflection in a plane containing the nuclei (symmetric), using the + above. The - is used to indicate that there is not.
For homonuclear diatomic molecules, the index g or u denotes the existence of a center of symmetry (or inversion center), and indicates the parity
of the total wave function. States of even parity with respect to inversion are denoted g for gerade (German for even), and states of odd parity are denoted u for ungerade (German for odd).
Ion
An ion is an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge. The name was given by physicist Michael Faraday for the substances that allow a current to pass between electrodes in a...
, as well as atomic
Atomic orbital
An atomic orbital is a mathematical function that describes the wave-like behavior of either one electron or a pair of electrons in an atom. This function can be used to calculate the probability of finding any electron of an atom in any specific region around the atom's nucleus...
and molecular orbitals.
Ionization states
Spectroscopists customarily refer to the spectrum arising from a given ionization state of a given elementChemical element
A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Familiar examples of elements include carbon, oxygen, aluminum, iron, copper, gold, mercury, and lead.As of November 2011, 118 elements...
by the element's symbol followed by a Roman numeral. The numeral I is used for spectral lines associated with the neutral element, II for those from the first ionization state, III for those from the second ionization state, and so on. For example, 'He I' denotes lines of neutral helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...
, and 'C IV' denotes lines arising from the third ionization state, C+++, of carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
.
Atomic and molecular orbitals
Before atomic orbitals were understood, spectroscopists discovered various distinctive series of spectral lines in atomic spectra, which they identified by letters. These letters were later associated with the azimuthal quantum numberAzimuthal quantum number
The azimuthal quantum number is a quantum number for an atomic orbital that determines its orbital angular momentum and describes the shape of the orbital...
, l. The letters, "s", "p", "d", and "f", for the first four values of l were chosen to be the first letters of properties of the spectral series observed in alkali metals. Letters for subsequent values of l were assigned in alphabetical order, omitting the letter "j":
| letter | name | | l |
|---|---|---|
| s | sharp | 0 |
| p | principal | 1 |
| d | diffuse | 2 |
| f | fundamental | 3 |
| g | 4 | |
| h | 5 | |
| i | 6 | |
| k | 7 | |
| l | 8 | |
| m | 9 | |
| n | 10 | |
| o | 11 | |
| q | 12 | |
| r | 13 | |
| t | 14 | |
| u | 15 | |
| v | 16 | |
| ... | ... |
This notation is used to specify electron configurations and to create the term symbol
Term symbol
In quantum mechanics, the Russell-Saunders term symbol is an abbreviated description of the angular momentum quantum numbers in a multi-electron atom. It is related with the energy level of a given electron configuration. LS coupling is assumed...
for the electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
states in a multi-electron atom. When writing a term symbol, the above scheme for a single electron's orbital quantum number
Azimuthal quantum number
The azimuthal quantum number is a quantum number for an atomic orbital that determines its orbital angular momentum and describes the shape of the orbital...
is applied to the total orbital angular momentum associated to an electron state.
Mnemonic
One mnemonicMnemonic
A mnemonic , or mnemonic device, is any learning technique that aids memory. To improve long term memory, mnemonic systems are used to make memorization easier. Commonly encountered mnemonics are often verbal, such as a very short poem or a special word used to help a person remember something,...
phrase for remembering the sequence S. P. D. F. G. H. ... is "Sober Physicists Don't Find Giraffes Hiding In Kitchens Like Mine". One is expected to remember that after the F, the letters in the sequence are alphabetical (excluding J).
There are a few other mnemonic
Mnemonic
A mnemonic , or mnemonic device, is any learning technique that aids memory. To improve long term memory, mnemonic systems are used to make memorization easier. Commonly encountered mnemonics are often verbal, such as a very short poem or a special word used to help a person remember something,...
phrases for remembering the sequence, for example:
- Smart People Don't Fail
- Silly People Drive Fast
Another mnemonic is: if you don't memorize the proper order, you will get a SPeeDy F!
Molecular Spectroscopic Notation
The spectroscopic notation of molecules uses Greek letters to represent the modulus of the orbital angular momentum along the internuclear axis.The quantum number that represents this momentum is the Λ.
Λ=0,1,2,3,...
Symbols: Σ,Π,Δ,Φ
For Σ states, one denotes if there is a reflection in a plane containing the nuclei (symmetric), using the + above. The - is used to indicate that there is not.
For homonuclear diatomic molecules, the index g or u denotes the existence of a center of symmetry (or inversion center), and indicates the parity
Parity (physics)
In physics, a parity transformation is the flip in the sign of one spatial coordinate. In three dimensions, it is also commonly described by the simultaneous flip in the sign of all three spatial coordinates:...
of the total wave function. States of even parity with respect to inversion are denoted g for gerade (German for even), and states of odd parity are denoted u for ungerade (German for odd).
See also
- principal quantum numberPrincipal quantum numberIn atomic physics, the principal quantum symbolized as n is the firstof a set of quantum numbers of an atomic orbital. The principal quantum number can only have positive integer values...
- azimuthal quantum numberAzimuthal quantum numberThe azimuthal quantum number is a quantum number for an atomic orbital that determines its orbital angular momentum and describes the shape of the orbital...
- electron configurationElectron configurationIn atomic physics and quantum chemistry, electron configuration is the arrangement of electrons of an atom, a molecule, or other physical structure...
- term symbolTerm symbolIn quantum mechanics, the Russell-Saunders term symbol is an abbreviated description of the angular momentum quantum numbers in a multi-electron atom. It is related with the energy level of a given electron configuration. LS coupling is assumed...
- X-ray notationX-ray notationX-ray notation is a method of labeling atomic orbitals that grew out of X-ray science. It is still traditionally used with most x-ray spectroscopy techniques including AES and XPS. In X-ray notation, every principal quantum number is given a letter associated with it.-Conversion:-Use:*X-ray sources...