Term
[Dual Nature of Light]
Wave: |
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Definition
-Explains physical properties of light itself.
-Physicist |
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Term
[Dual Nature of Light]
Particle (Photon): |
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Definition
-Explains how light interacts with matter.
-Biologist/Chemist |
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Term
1. Relation between frequency and wavelength: 2. Speed of light in other medium? |
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Definition
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Relation between energy and frequency (or wavelength): |
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Definition
- Smaller Wavelength →Higher Frequency → More Energy
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Term
| What are the ways light interacts with matter? |
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Definition
Light can be: - Reflected
- Refracted
- Scattered
- Emitted
- Absorbed
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Term
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Definition
| Transfer of energy from photon to atom or molecule which produces transition from a lower energy to a higher energy level. |
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Definition
| Production of photon of energy from atom or molecule which is originally in a higher energy level and which returns atom or molecule to a lower energy level. |
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| What are the 5 main components of a spectrophotometric experiment? |
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Definition
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Term
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Definition
- The fraction of incident light that passes through a sample.
- T = P/P0
- P0 is the irradiance (radiant power) striking the sample and P is irradiance emerging from other side of sample.
- P ≤ P0
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Definition
- Most useful quantity for chemical analysis.
- A = log(P0/P) = -log(T)
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Definition
Aλ=ελbc - The reason why absorbance is so important is that absorbance is proportional to the concentration of light-absorbing molecules in the sample.
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Term
| Limitations of Beer-Lambert Law: |
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Definition
Works well for dilute solutions (≤ 0.01 M) of most absorbing substances. Light must be monochromatic Pathlength must be constant (square cuvette) (typically is 1 cm) Sample should not: Fluoresce or phosphoresce Scatter light (heterogeneous) Change its chemical composition
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Term
| Common Cuvets for Ultraviolet and Visible Measurements: |
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Definition
- Standard 1-cm path
- Cylindrical
- Microcells
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