@ Salisu, the value of maximum absorption (λmax) is important for several reasons. 1. This wavelength is characteristic of each compound 2. It provides information on the electronic structure of the analyte 3. It ensures highest sensitivity and minimize deviations from Beer's Law. We can determine λmax by plotting absorbance vs wavelength in graph. Moreover, the absorbance maximum is used instead of some other point on the absorption curve because the maximum is the most reliable position to measure. The reason for this can be easily understood by imagining what would happen if you accidentally sampled a spot 1 nm off from the actual maximum.

Please define the meaning of " complex Compound" . Why? Is it a big molecule WITHOUT metal or is it a metal complexe like NMR contrast agents (complexes of Gadolinium (III) a.s.o. .... p.e.).

After the synthesis, you must purify and dry the compound. You must have a T.L.C with one spot, a correct elemental analysis, MS and NMR and IR too.

With a pure compound, its initial weight for the concentration in a pure and dried UV-Vis solvent leads to a reproducible and correct value of λmax.

Deviations from Beer 's Law occur for several reasons like pH , impurities, aggregation (dimer formation with increasing concentration p.e.).

Please define spectrometer (single , double beam, diodearray UV-Vis spectrometers).

To your question:

λmax determination gives , like NMR, MS, IR or FTIR and TLC , a lot of infos about your " complex compound". You must give these values when you write a report or publish a paper.

At this time , you can obtain UV-Vis spectra of translucent and opaque samples.

There are a plenty of books and introductions in UV-Vis spectroscopy at normal temperature (e.g. room temperature).

Shows your compound fluorescence in solution?

First of all, the absorption of photons (light from a spectrophotometer) by a sample occurs when the frequency of the incoming photons resonates with the electronic frequency of the absorbing sample.

For an impure sample (or polyphasic material), there is a likelihood of several absorption peaks in the spectrum. However, the peak absorption at what wavelength (λmax) is most important vis-a-vis material's properties like energy bandgap, sensitivity, electronic structure etc.

λmax, therefore, gives a vivid indication of the properties of your sample for identification and further analysis. It is good practice to use pure samples, in order to have a unique λmax. FTIR and Raman spectroscopic can give further details about the sample of interest.