usually IR has better penetration..but there may be exceptions e.g. for certain glasses and also depending on the wavelength..you have to check this for the individual case

First of all it depends to the material studied, and for me i guess that IR is more better then UV cause its wavelength is bigger than UV.

Typically, IR has more penetration ability. But it is true that you can say this ability depends on the material too. But in general longer the wavelength of the material, higher the penetration ability.

Here is a simplified explanation I found online.

https://chem.libretexts.org/Courses/Sacramento_City_College/SCC%3A_CHEM_330_-_Adventures_in_Chemistry_(Alviar-Agnew)/11%3A_Nuclear_Chemistry/11.06%3A_Penetrating_Power_of_Radiation#:~:text=The%20ability%20of%20each%20type,the%20more%20dangerous%20they%20are.

The absorption coefficient is always larger for UV compare to IR. However, it depends on the material and a particular wavelength. Some substances may show strong IR absorption, but it does not absorb over a wide IR range. NIR spectroscopy is based on absorption by the chemical bands. In general, UV light much stronger absorbed by any substance compared with IR.

Hi;

Infrared and ultraviolet are electromagnetic radiations whose spectral bands are located on either side of visible light. Infrared is above 0.8 μm (wavelength of red) and ultraviolet is below 0.4 μm (wavelength of violet). For both radiations, the energy incident on a material can be reflected, absorbed or transmitted depending on the optical characteristics of the material. In addition, in both cases, absorption generally occurs at the surface of materials with a shallow depth of penetration. This characteristic is particularly marked for ultraviolet light.

With my best regards

Hi ...Its depending on the type of material...according to light _ matter interaction principle also the wavelength.