7 votes
Accepted

When pigments absorb light only around a single particular wavelength, why aren't they still white?

You are right that an individual transition from one state to another by absorption of a photon is connected to a very well defined energy. However, an absorption band in UV/VIS results from ...
6 votes

When pigments absorb light only around a single particular wavelength, why aren't they still white?

As others have brought up, indeed the absorption features of most compounds with electronic transitions in the visible light range are rather broad, and this breadth is important in generating a ...
6 votes

When pigments absorb light only around a single particular wavelength, why aren't they still white?

Some types of light absorbance show very narrow lines while others show broad peaks. Atomic spectra have sharp lines when the atoms are in the gas phase. One example is the absorption of sunlight by ...
  • 33.6k
6 votes

When pigments absorb light only around a single particular wavelength, why aren't they still white?

Color perception is a complex topic and one cannot make generalized statements. If you are seriously investigating and want to have a deeper understanding, then get hold of a beautiful book called The ...
  • 35.1k
6 votes

The reason for selection of wavelengths in the spectrophotometry of Quinoline Yellow SS

The experiment in your link pg 31 is "Path Length Dependence of Absorbance Values". As you stated, quinoline absorption spectrum has a dip near 337 nm. The reason for choosing the wavelength ...
  • 35.1k
3 votes

Does ionization energy play a role in absorption spectrometry of non metals?

Your intuitive argument is not that far off. I am sure you are talking about atomic absorption spectrometry (AAS). Analyzing metals is routine but analyzing non-metals is indeed near impossible ...
  • 35.1k
2 votes

Solubility of nitrogen dioxide in sodium hydroxide

A numerous studies have shown that the absorbtion of $\ce{NO2}$ in alkaline solutions is due to the reaction (For example, Ref.1): $$\ce{2NO2 + 2OH- -> NO2- + NO3- + H2O} \tag1$$ Thus, as Poutnik ...
1 vote
Accepted

Normalized absorbance/transmittance definition

Recall the more familiar definition of light transmittance $T = \frac{I}{I_o}$, many instruments quote percent transmittance as $\%T = 100\frac{I}{I_o}$ Normalized transmittance is nothing but the ...
  • 35.1k
1 vote
Accepted

Why is the IUPAC definition of adsorption so different from other definitions?

In a short email correspondence with the IUPAC, where I raised these issues, I was told that efforts are being made to revise the Gold Book. Jim McQuillan, COB of the Commission on Physiochemical ...
1 vote

Improving efficiency of absorption refrigerator (ammonia+hydrogen)

I worked as a production manager for a company that manufactured similar units. On these absorption units, the inside temperature is directly related to the ambient temperature. The warmer it’s ...
  • 11

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