Question

UV-VIS absorption spectra are broad band spectra. Explain.

Answer 1

Every molecule has some absorption for UV rays. And at a particular wavelength of UV rays, there is a maximum absorption. This is called asλmax. This λmax is a characteristic (specific) for every molecule. When we scan the sample using the UV rays (usually between 200 nm-400 nm), the sample absorbs the UV rays accordingly and gives a broad spectrum. This means that the sample absorbs all the different wavelengths of the UV rays and gives an absorption value for each wavelength absorbed, along with the wavelength at which maximum absorption took place i.e., λmax. So we get an intense peak for the λmax and that peak denotes the λmax of the sample.