Radiation absorbing surfaces

A substantially radiation absorbing composite surface, comprising:

• (a) a replicated microstructured layer characterized by a plurality of randomly positioned discrete protuberances of varying heights and shapes, which protuberances have a height of not less than 20 nanometers nor more than 1500 nm, and the bases of which contact the bases of substantially all adjacent protuberances, and
• (b) an overcoating of a thin film of at least one metal having a thickness in the range of 40 to 200 nanometers.

An article having a substantially radiation absorbing surface, said article comprising:

• a substrate having on at least one surface thereof,
• (a) a layer of an oxide or hydroxyoxide of a metal, selected from the group consisting of aluminum, magnesium and zinc or alloys thereof, which layer is a substantially complete conversion of a thin-film of said metal, the thickness of said thin-film prior to conversion being at least 5 nanometers and exhibiting a surface after said conversion characterized by a plurality of randomly positioned discrete protuberances of varying heights and shapes, which protuberances extend from said substrate surface a distance of not less than 20 nanometers nor more than 1500 nm, and the bases of which contact the bases of substantially all adjacent protuberances, and
• (b) an overcoating upon said oxide or hydroxyoxide layer, which overcoating is a contiguous connected thin layer of at least one metal having a thickness in the range of 40 to 200 nanometers.

A process for preparing a substantially radiation absorbing composite surface, said process comprising the steps of:

• (a) providing a replicated microstructured layer characterized by a plurality of randomly positioned discrete protuberances of varying heights and shapes, which protuberances have a height of not less than 20 nanometers nor more than 1500 nm, and the bases of which contact the bases of substantially all adjacent protuberances, and
• (b) overcoating said microstructured layer with a contiguous connected thin layer of metal having a thickness in the range of 40 to 200 nanometers.

The process of preparing a substantially radiation absorbing surface, said process comprising

• (a) providing a substrate having on at least one surface thereof a layer of an oxide or hydroxyoxide of a metal, selected from the group consisting of aluminum, magnesium and zinc or alloys thereof, which layer is a substantially complete conversion of a thin-film of said metal, the thickness of said thin-film prior to conversion being at least 5 nanometers and exhibiting a surface after said conversion characterized by a plurality of randomly positioned discrete protuberances of varying heights and shapes, which protuberances extend from said substrate surface a distance of not less than 20 nanometers nor more than 1500 nm, and the bases of which contact the bases of substantially all adjacent protuberances, and
• (b) overcoating upon said oxide layer a contiguous connected thin layer of at least one metal having a thickness in the range of 40 to 200 nanometers.