content_image/891861.jpg content_image/891863.jpg content_image/891862.jpg content_image/891857.jpg content_image/891858.jpg content_image/891859.jpg content_image/891860.jpg
group, an arylene group, a carbonyl group, a sulfonyl group, a carbonyloxy group, a carbonylamino group, a sulfonyla› mido group, an ether group, a thioether group, an amino group, a disulfide group, an acyl group, an alkylsulfonyl group, ----CH=CH-, -C=C-, an aminocarbonylamino group, an aminosulfonylamino group or the like. The bivalent connecting group may have a substituent. The same substitu› ents as mentioned above with respect to R 1 to R $^{13 }$can be employed. Preferably, Z is a single bond or a substituent exhibiting no electron withdrawing properties, such as an alkylene group, an arylene group, an ether group, a thioether group, an amino group, ----CH=CH-, an aminocarbony› lamino group or an aminosulfonylamino group. More prefer› ably, Z is a single bond, an ether group or a thioether group. Most preferably, Z is a single bond. 

Specific examples of the onium ions of the general formula (VIII) will be shown below, which are however nonlimiting. 

<img src='content_image/891861.jpg'>

<img src='content_image/891863.jpg'>

<img src='content_image/891862.jpg'>

<img src='content_image/891857.jpg'>

<img src='content_image/891858.jpg'>

<img src='content_image/891859.jpg'>

<img src='content_image/891860.jpg'>

-continued 

