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  1. #1
    Mustafa Umut Sarac's Avatar
    Join Date
    Oct 2006
    İstanbul - Türkiye
    35mm RF

    Sensitizing Dyes for Silver Halide Recording Materials

    H. I. B jelkhagen
    Recording Materials

    Acridine orange

    3,6"-(dimethyl amino)-acridine hydrocIoride hydrate
    Auramine 0 (Basic yellow 2)
    4,4' -(imidocarbonyl)-"-(N,N ,-dimethylaniline) hydrochloride
    Dithiozanin iodide
    3,3' -diethyl-thiacarbocyanine iodide
    Eosin Y (Eosin yellowish)
    2' ,4' ,5' ,7' -tetrabromofluorescein disodium salt
    Erythrosin B (Iodesine)
    tetraiodfluoresine disodium salt
    Isocyanine iodide
    1,1' -diethyl-2,4' -cyanine iodide
    Kryptocyanine (Rubrocyanine)
    1,1' -diethyl-4,4' -carbocyanine iodide
    Orthochrom T
    1,1' -diethyl-6,6' -dimethylisocyanine
    1,1' -diethyl-6-ethoxy-6' -methoxyisocyanine bromide
    Pinacyanol bromide
    l,l'-diethyl-2,2' -carbocyanine bromide
    Pinacyanol chloride (Quinaldine blue)
    1,1' -diethyl-2,2' -carbocyanine chloride
    Pinacyanol iodide (Sensitol red)
    l,l'-diethyl-2,2'-carbocyanine iodide
    1-methyl-2-p-dimethylaminostyryl pyridine
    Pinaverdol (Sensitol green)
    1,1' ,6-trimethylisocyanine iodide
    Pseudocyanine iodide
    l,I'-diethyl-2,2'-cyanine iodide
    Rhodamine B
    N,N,N' ,N' ,tetra ethylrhodamine hydrochloride

    Sensitizing Dyes
    The most difficult part of emulsion-making is to find suitable sensitizers
    for, in particular, fine-grained materials. Commercial companies are usually
    very secretful about sensitizers they apply to their emulsions, which is why
    it is so hard to find any publication that gives comprehensive description of
    dyes or sensitizers. In particular, sensitizers for the deep-red part of the
    spectrum are difficult to find. There are two types of sensitization of photographic
    I. Chemical sensitization which refers to methods to obtain the highest
    possible sensitivity of the silver-halide crystals. Here, sulfur, gold and reduction
    sensitization are common.
    2. Spectral sensitization which refers to methods to sensitize the silverhalide
    grains to light in a region of the spectrum in which they would normally
    not absorb. Here, special dyes are used.
    In this section the second type of sensitization is of main interest.
    Chemical sensitization of holographic silver-halide emulsions has, in general,
    been discussed by Pantcheva et al. [2.68]. Emulsions intended for short
    exposure times using pulsed lasers have been treated by Pangelova et al.

    As already mentioned, pure silver-halide crystals are only sensitive to
    light in the UV and violet parts of the spectrum. According to the Grotthus-
    Draper law, only light which is absorbed can cause a chemical change.
    The formation of a latent image is a chemical change. Up to a certain
    photon energy, the silver-halide crystal alone can absorb the radiation energy
    according to Planck's law (E = hll). The energy is high enough to raise
    the silver-halide molecule from the ground state to a higher state to free an
    electron which can combine with a silver ion and thus form a latent-image
    speck. For light of longer wavelengths the energy of individual photons are
    not high enough and no photon absorption takes place. Therefore, in order
    to record at other wavelengths within the electromagnetic spectrum the
    emulsion has to absorb the radiation in some way and transfer the energy to
    the silver-halide grain to produce a latent image. There are special dyes that
    can absorb light of different wavelengths. At certain wavelengths the molecules
    of the dye can absorb the radiation and the molecule is then raised to
    a higher state. This means that an electron is raised from the valence band
    to the conduction band. Now two things could happen:
    Either the electron is directly transferred to the silver-halide crystal to
    form· metallic silver by combining with a silver ion (electron transfer); or
    the electron formed by the dye will bring about an excitation of the silverhalide
    crystal, causing a bromide ion to part with an electron (energy
    transfer). The duration of the exited state of the dye molecule which is responsible
    for the sensitization is very short, about 10-11 s. Both electron and
    energy transfer can take place depending on type of dye. By such mechanisms
    it is possible to affect the silver-halide crystals to form a latent image
    at radiation of various wavelengths.
    Not only must such a dye absorb the light of a certain wavelength but
    also must it adsorb to the silver-halide crystal surface. Only if the dye is in
    intimate contact with the grain can it transfer the effect of the light. The
    force acting between the dye and halide molecules is of the Van der Waal
    type. If the dye is not in good contact with the grain or if it is located in
    the gelatin matrix the effect of it is a light-filtering function which actually
    reduces the intensity of the illumination in this region.
    The dyes used for the sensitization are mainly the cyanine dyes. They
    can be divided into two classes: the true cyanines and the merocyanines.
    Often the chalkocarbocyanines are used. More about these dyes can be
    found in Duffin's book [2.36]. Some of the dyes employed in Lippmann
    emulsions and holographic emulsions have already been mentioned and are
    listed in Table 2.4.
    A special sensitizer mentioned in one of the Russian papers that is
    claimed to be very good for holograms at the ruby-laser wavelength
    (694 nm) is the: 3-allyl-3' - ethyl-4' ,5' -diphenyl-4-keto-5(I "-ethyl-dihydroQuinolilidene-
    4"-ethylidene) thiazolinothiazolocyanine bromide [2.70].

    2.68 M. Pantcheva, T. Petrova, N. Pangelova, A. Katsev: Chemical sensitization of
    fine-grain silver halide emulsions for holographic recording, in H%graphy'89,
    ed. by Y.N. Denisyuk, T.H. Jeong. Proc. SPIE 1183, 128-130 (1990)
    2.69 N. Pangelova, T. Petrova, A. Katsev, M. Pantcheva: Silver halide materials for
    pulsed holographic recording, in Holography'89, ed. by Y.N. Denisyuk, T.H.
    Jeong. Proc. SPIE lIS3, 131-133 (1990)
    2.70 N.S. Gafurova, L.G. Logak, Kh.Kh. Fassakhova, R.K. Khakimova, R.K. Tep-
    10va, LN. Zelinsky, V.T. Chernikh
    : Silver halide photographic material having a
    flexible base for the use in pulse holography. Proc. 14th Int'! Congr. on High
    Speed Photography and Photonics, ed. by B.M. Stepanov (Moscow, October
    19-24, 1980) pp.437-439
    2.36 G.F. Duffin: Photographic Emulsion Chemistry (Focal, London, New York

  2. #2

    Join Date
    Aug 2012
    The dyes which you cite are all commercial dyes and have been used to sensitize emulsions for about 100 years. The Lumiere brothers sensitized their color process, Autochrome, in 1907. Their silver/bromide emulsion contained Orthochrom T, erythrosin, and ethyl violet (which is not on your list). see:


    Modern films contain dyes which are typically cyanine derivatives. These dyes are not stable, but since they are exposed to light only briefly, that does not matter. One dye which has been used to sensitize for red light is Sand's SDA3057, which has been discussed on APUG.



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