Question

Rhodamine G is a popular fluorescent tag and it absorbs light at 475 nm. A series of fluorescence emission experiments were performed to examine the emission characteristics of rhodamine and one data point is given below. What is the most likely reason the emission intensity zero?

Experiment	λ excitation (nm)	λ emission (nm)	[Rhodamine] / mg/mL	Emission Intensity (Unitless)
1	475	425	0.01	0.0

	a.	The intensity is being measured at a shorter wavelength than excitation so no emission would be seen.
	b.	Rhodamine is not a suitable molecule for a fluorescence experiment.
	c.	The sample concentration must be above the self quenching concentration of Rhodamine.
	d.	Rhodamine releases all of the absorbed energy through non-radiative processes.

Answer 1

The answer is a. The intensity is being measured at a shorter wavelength than excitation so no emission would be seen. Intensity measurement need to be measured at the particular wavelength of emission in order to be detected.