film like the recording layer obtained in example 2 and in this recording layer too there took place the same reversible reactions as in the recording layer of example 2 upon exposure to two types of light source differing in wavelength further in the case of this example the half life period of flf 0 was one week and that of the colored version was more than one day in the dark place at room temperature which signifies a remarkable improvement of stability in comparison with single use of flf 0 in example 2 the half life period in this case being about one hour the flf 0 to octadecane mixing ratio of 1 2 is most preferred but a similar effect is obtainable when said mixing ratio is in the range of 1 0 5 to 1 10 use of the fulgide having a c 18 long chain keto group of this example is most desirable for producing the recording media of this invention a similar effect can be obtained when c 14 to 22 in case c greater than 31 it was difficult to obtain the starting fulgide when c less than 5 it was impossible to obtain a langmuir blodgett film a benzene solution of a 1 1 mixture of flf 0 and stearic acid was prepared and a recording layer was formed by using this solution according to the process of example 2 this recording layer like that of example 2 was a uniform ultra thin film and there took place the same.