The cationic dye may be chosen from azo dyes, azomethine dyes, methine dyes and xanthene dyes.

优选地，阳离子染料选自偶氮染料、偶氮甲碱染料、次甲基染料和？吨染料。

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Near-infrared cyanine dyes can be obtained by increasing length of conjugated methine chain in dye molecules.

菁染料光谱性能优良，可通过增加甲川链长度，获得近红外菁染料。

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