The infra-red spectrum lies between:

The infrared (IR) spectrum lies between the visible and microwave regions of the electromagnetic spectrum. It spans wavelengths ranging from approximately 0.7 micrometers (µm) to 1 millimeter (mm). In terms of frequency, it covers the range from about 300 gigahertz (GHz) to 400 terahertz (THz).

Here's a breakdown of the regions within the infrared spectrum:

Near-Infrared (NIR): This region ranges from about 0.7 µm to 2.5 µm and is often used in various applications, including remote sensing, fiber optics, and some analytical chemistry techniques.

Mid-Infrared (MIR): The mid-infrared region spans from around 2.5 µm to 25 µm. It is commonly used in spectroscopy, chemical analysis, and the identification of molecular vibrations.

Far-Infrared (FIR): The far-infrared region extends from approximately 25 µm to 1 mm. It is often used in studies of rotational spectroscopy and for applications such as thermal imaging.

These divisions are approximate, and the exact boundaries between these regions can vary depending on the context and the specific field of study.