Deslandres table¶

In electronic spectroscopy, constructing a Deslandres table is a useful method to assign vibronic transitions.

Version: v1 · 2026-09-28 · History
Domain-specific #: 8932
Domain group: Natural Sciences
Origin domain: Physics
Subdomains: Molecular Spectroscopy, Vibronic Spectroscopy → Physics

Core Idea¶

Deslandres table is treated here as the recurring cross-domain formal modeling identity summarized by this source-grounded definition: In electronic spectroscopy, constructing a Deslandres table is a useful method to assign vibronic transitions. In electronic spectroscopy, constructing a Deslandres table is a useful method to assign vibronic transitions. In such a table, the frequencies of the lines seen in an electronic spectrum of a molecule are collected so that the differences in energy between adjacent columns or rows are all the same (within experimental error).

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The Light-Line Sorting Grid

When a molecule soaks up light, it makes a pattern of thin lines, like a barcode. Scientists write the line numbers into a grid, arranged so that the steps from one column to the next, and one row to the next, are always the same size. That grid, a Deslandres table, helps them figure out what jump each line came from.

Sorting Light Lines Into a Grid

When a molecule absorbs or gives off light, it jumps between two main energy levels, and at the same time it can change how strongly it is vibrating. Each combination makes a slightly different spectral line, so you see lots of close-together lines. A Deslandres table sorts these line frequencies into rows and columns. Each column goes with one vibration level of the lower state, and each row with one vibration level of the upper state. If the table is filled correctly, the jump in frequency from one row to the next is the same in every column, and the same goes for columns, which tells scientists they have matched each line to the right vibrations.

Vibronic Transition Assignment Table

In electronic spectroscopy, a molecule jumps from a lower electronic state to an excited one, and at the same time its vibrational level can change, so one electronic transition produces many closely spaced lines called vibronic transitions. A Deslandres table is a way to assign those lines. You arrange the measured line frequencies in a grid so that the difference between neighboring columns, and between neighboring rows, is constant within experimental error. When the table is correct, columns correspond to vibrational levels of the lower electronic state and rows to those of the upper state. The spacing between two rows is the same in every column because it equals the energy gap between two vibrational levels of the same electronic state. The line intensities are set separately by the Franck-Condon principle.

A Deslandres table is a tool in molecular electronic spectroscopy for assigning vibronic transitions, the lines produced when an electronic transition from a lower-lying state to an excited state is accompanied by changes in vibrational level. The observed line frequencies are arranged in a two-dimensional array so that the differences between adjacent columns and between adjacent rows are constant within experimental error. In a correctly constructed table, the columns index the vibrational quantum number of the lower electronic state (v'') and the rows that of the upper state (v'). The constancy follows directly from the level structure: the difference between two successive rows is the energy separation of two given vibrational levels of the upper state, which is independent of the lower-state level involved, and likewise for columns. Line intensities, by contrast, are governed by the Franck-Condon principle and do not affect the arrangement. Filling the table therefore converts a dense list of frequencies into an assignment of each line to a (v', v'') pair.

Scope of Application¶

Documented setting. In electronic spectroscopy, constructing a Deslandres table is a useful method to assign vibronic transitions.
Documented setting. In such a table, the frequencies of the lines seen in an electronic spectrum of a molecule are collected so that the differences in energy between adjacent columns or rows are.
Documented setting. The intensity of the lines is governed by the Franck–Condon principle.
Documented setting. When a Deslandres table is filled correctly, the columns represent the vibrational energy levels of the lower electronic state (v ), while the rows represent those for the upper electronic state (v ' ).
Documented setting. Clearly, the difference in energy between two successive rows (columns) must remain constant for any column (row) in the table because this represents the energy difference of two given vibrational levels.

Clarity¶

A clear use of Deslandres table names the carrier, the operative relation, and the conditions under which the source treats the identity as present. The minimal definition is In electronic spectroscopy, constructing a Deslandres table is a useful method to assign vibronic transitions. The strongest recognition evidence in the frozen account is: In such a table, the frequencies of the lines seen in an electronic spectrum of a molecule are.

Manages Complexity¶

Deslandres table compresses multiple cross-domain formal modeling details into a stable diagnostic relation. The source shows both the central mechanism—thus, by completing a Deslandres table it is easy to assign the correct vibrational quantum numbers v and v ' for the transition, allowing important molecular properties to be calculated, such as the dissociation energy.—and the practical consequence—clearly, the difference in energy between two successive rows (columns) must remain.

Abstract Reasoning¶

Type the carrier. Identify the cross-domain formal modeling entities to which the claim applies.
State the relation. Use the source-grounded identity: In electronic spectroscopy, constructing a Deslandres table is a useful method to assign vibronic transitions.
Check operation and conditions. In electronic spectroscopy, constructing a Deslandres table is a useful method to assign vibronic transitions.
Demand recognition evidence.

Knowledge Transfer¶

Within the home domain. Knowledge about Deslandres table transfers literally when a new case preserves the same carrier type, relation, and recognition test. In electronic spectroscopy, constructing a Deslandres table is a useful method to assign vibronic transitions. In such a table, the frequencies of the lines seen in an electronic spectrum of a molecule are collected so that the differences in energy between adjacent columns or rows are all the same (within experimental error). Beyond the home domain. No canonical parent is asserted for Deslandres table.

Neighborhood in Abstraction Space¶

Deslandres table sits in a sparse region of the domain-specific corpus (75^th percentile for distinctiveness): few abstractions share its structure, so a faithful description tends to retrieve it precisely.

Family — Unclustered & Miscellaneous (2551 abstractions)

Nearest neighbors

Computed from structural-signature embeddings · 2026-10-08