A light-absorbing material includes a compound represented by the formula (1) below. In the formula (1), L.sup.1 to L.sup.3 are each independently represented by the formula (2) or (3) below:

##STR00001##

A holographic recording medium composition comprising component (e): a compound having an isocyanate group or an isocyanate-reactive functional group and further having a nitroxyl radical group, wherein component (e) contains component (e-1) below: component (e-1): a compound having a heterobicyclic ring structure or a heterotricyclic ring structure, the heterobicyclic ring structure or the heterotricyclic ring structure being obtained by replacing a carbon atom in a bicyclic ring structure or a tricyclic ring structure by the nitroxyl radical group.

A nonlinear optical material is represented by the following formula (1).

##STR00001##

A method of recording data to a layer (101) of a recording medium in which an organic luminescent precursor composition is irradiated with a first light beam (103) and a second light beam (105), the first light beam having a write wavelength for conversion of the organic luminescent precursor composition to an organic luminescent composition and the second light beam having a write inhibition wavelength for inhibiting conversion of the organic luminescent precursor composition to the organic luminescent composition. The second light beam has a central area and a surrounding area; an intensity of the second light beam in the central area being lower than an intensity of the second light beam in the surrounding area. The first light beam extends across the central area and the surrounding area of the second light beam surrounds the first light beam.

A method of recording data to a layer (101) of a recording medium in which an organic luminescent precursor composition is irradiated with a first light beam (103) and a second light beam (105), the first light beam having a write wavelength for conversion of the organic luminescent precursor composition to an organic luminescent composition and the second light beam having a write inhibition wavelength for inhibiting conversion of the organic luminescent precursor composition to the organic luminescent composition. The second light beam has a central area and a surrounding area; an intensity of the second light beam in the central area being lower than an intensity of the second light beam in the surrounding area. The first light beam extends across the central area and the surrounding area of the second light beam surrounds the first light beam.

A nonlinear optical material is represented by the following formula (1). At least one selected from the group consisting of R.sup.1 to R.sup.5, at least one selected from the group consisting of R.sup.6 to R.sup.10, and at least one selected from the group consisting of R.sup.11 to R.sup.15 are represented by the following formula (2).

##STR00001##

Storage media are provided. A substrate has an array of addressable locations thereon, each addressable location adapted to be physically associated with a collection of molecules, each collection comprising at least a first subcollection of molecules and a second subcollection of molecules. The molecules in the collection are selected from a set of unambiguously identifiable molecules, the set comprising at least a first subset of molecules and a second subset of molecules. Each molecule in the first subset is identifiable by a first physical property, and each molecule in the second subset is identifiable by a second physical property, different from the first physical property. Each molecule in the set is uniquely associated with a predetermined position in a numerical value, wherein the presence of the molecule in the collection indicates a predetermined digit at the associated position and the absence of said molecule in the collection indicates a zero at said associated position.

A recording medium according to one embodiment of the present disclosure includes a recording layer and an optical thin film. The recording layer includes a heat-sensitive color-developing composition and a photothermal conversion material. The photothermal conversion material absorbs a wavelength in an infrared region and generates heat. The optical thin film is provided on one surface of the recording layer. The optical thin film reflects the wavelength in the infrared region and transmits a wavelength in a visible region.

A recording medium according to one embodiment of the present disclosure includes a recording layer and an optical thin film. The recording layer includes a heat-sensitive color-developing composition and a photothermal conversion material. The photothermal conversion material absorbs a wavelength in an infrared region and generates heat. The optical thin film is provided on one surface of the recording layer. The optical thin film reflects the wavelength in the infrared region and transmits a wavelength in a visible region.

A holographic recording medium composition comprising component (e): a compound having an isocyanate group or an isocyanate-reactive functional group and further having a nitroxyl radical group, wherein component (e) contains component (e-1) below: component (e-1): a compound having a heterobicyclic ring structure or a heterotricyclic ring structure, the heterobicyclic ring structure or the heterotricyclic ring structure being obtained by replacing a carbon atom in a bicyclic ring structure or a tricyclic ring structure by the nitroxyl radical group.