This is luminescence for sure, which includes various types of mechanisms, among them fluorescence, phosphorescence, electroluminescence, chemiluminescence, etc. Your material seems to convert UV light into visible light, i.e. into photons of higher wavelength. If the phenomenon immediately stops once UV light is switched off, this is probably fluorescence.

Alain

This is luminescence for sure, which includes various types of mechanisms, among them fluorescence, phosphorescence, electroluminescence, chemiluminescence, etc. Your material seems to convert UV light into visible light, i.e. into photons of higher wavelength. If the phenomenon immediately stops once UV light is switched off, this is probably fluorescence.

Alain

It seems that your compound showed well fluorescence, what is it made of? is it a nanoparticle? check it's emission intensity by a spectrofluorometer in uv-visible range and you will see a very nice peak.

Luminescence is a general word which should be used when we do not know the exact mechanism of light emission. It includes all the processes listed by Dr. Alain. Fluorescence is a specific process which refers to transitions from and to certain electronic states. There are very advanced experimental ways of determining the exact mechanism of light emission based on time based data and light emission decay. 

luminescence is a general light emitting phenomena and fluoroscence is a part of it in which there is a fast decay of electrons from higher excited state to lower state without going into any intermediate triplet state and luminescence can also be done by phosphorescence in which there is a time lag for de excitation you can differentiate these two on time scale................fluoroscence take less time (nano seconds range) and phosphorescence takes long time in the range of milli seconds or more.

To better determine the nature of the light emission you are observing you should consider carefully the nature of the material and possible light emitting mechanisms.  To gain further insight into the light emitting mechanism, I reccommend performing time-dependent luminsecent studies.  By measuring the lifetime of the luminescent peak, you can determine the probable mechanism of light emission by considering if the emission is on the order of picoseconds, nanoseconds, hundreds of nanoseconds, or microseconds.

You can call it luminescence for sure, because fluorescence is a variation of luminescence. That wouldn't be a mistake.

Fluorescence is just a type of fluorescence that appears about a nanosecond or so after excitation.  To complicate matters, one can also talk about phosphorescence which applies if the luminescence appears well after excitation.  In your case, this looks like fluorescence.  If you are in any doubt, then just call it luminescence.

All what is said above is right. To add a touch of basic aspects:

Fluorescence results from a transition between two states with the same spin (usually between two singlet states: S = 0, multiplicity 2S+1 =1). This process is allowed by the spin rule (deltaS = 0) and is therefore fast.

Phosphorescence results from a transition between two states with different spin; in organic compounds, usually, between an excited  triplet state with S = 1 (multiplicity 2S+1 = 3) and the ground singlet state. The phenomenon is forbidden by the spin rule and implies change of the spin of one electron. It is slow.

The term "luminescence" indeed cover these two phenomena, among others. It has been coined by the German physicist Wiedemann in 1888 (Annalen der Physik 270 (7), 446-462, 1888; Ueber Fluoreszenz und Phosphorescenz I. Abhandlung") to distinguish it from incandescence (emission of light by any compound under heating and not involving transitions between electronic states, also called black-body emission).

Luminescence for sure since it includes different types of emission behaviors as mentioned earlier. An easy way to characterize the nature of this luminescence is by doing time resolved measurements such as laser flash photolysis nansecond transient absorption spectroscopy.

Also a quick way to see if both singlet and triplet states are present substantially, see the effect of oxygen removal by purging Argon or by freeze pump thaw, triplet states should be sensitive to presence of oxygen.