Physical chemistry
Electronic spectroscopy
Electronic spectroscopy measures transitions between electronic states and quantifies absorption with Beer–Lambert law.
A photon of suitable energy promotes an electronic transition. Vibrational structure often overlays an electronic band; intensity depends on transition probability and environment.
Absorption and concentration
Electronic spectroscopy measures transitions between electronic states and quantifies absorption with Beer–Lambert law.
Definition: Core definition
Absorbance A is the base-10 logarithm of incident-to-transmitted intensity; dilute solutions approximately obey Beer–Lambert.
Example: Worked example
Apply the model to a simple case: With ε in L mol⁻¹ cm⁻¹, c in mol L⁻¹ and l in cm, doubling concentration in the linear range doubles A.
Solution
With ε in L mol⁻¹ cm⁻¹, c in mol L⁻¹ and l in cm, doubling concentration in the linear range doubles A.
Absorbance A is the base-10 logarithm of incident-to-transmitted intensity; dilute solutions approximately obey Beer–Lambert.
| Quantity | Model / rule |
|---|---|
| Key relation | Electronic spectroscopy measures transitions between electronic states and quantifies absorption with Beer–Lambert law. |
| Meaning / use | With ε in L mol⁻¹ cm⁻¹, c in mol L⁻¹ and l in cm, doubling concentration in the linear range doubles A. |
In the linear range, how does absorbance A change when concentration doubles?
Which statement best matches the model described?
References
- Nicholas J. Turro et al. (2010). Modern Molecular Photochemistry