A salt comprising a group represented by the formula (aa):
wherein X
a
and X
b
independently each represent an oxygen atom or a sulfur atom, and X
1
represents a C1-C12 saturated hydrocarbon group which has a moiety represented by formula (1
a
) or (2
a
):
一种盐,其由公式(aa)表示的基团组成:其中Xa和Xb分别独立地表示氧原子或
硫原子,而X1表示具有由公式(1a)或(2a)表示的基团的C1-C12饱和碳氢基团。