NIR spectroscopy is a vibrational spectroscopy, similar to infrared (IR) or Raman techniques, in which the incident electromagnetic radiation probes molecular vibrations, i.e. oscillating changes in bond lengths (stretching vibrations) and angles between these bonds (deformation vibrations) [3,4,14].

Near-infrared spectroscopy (NIRS) is an optical technique of potential value in the study of the newborn because the method is capable of noninvasively providing crucial information concerning cerebral hemoglobin oxygen saturation, cerebral blood volume, and cerebral oxygen delivery/metabolism.

In summary, NIR is a different analytical method than IR, although both are types of vibrational spectroscopy. NIR is faster and easier to handle than IR. It does not require sample preparation and can provide information about the bulk material. It is also versatile.