How do I add special text symbols and characters in Photoshop CS?

Hi everybody,
I'm building an image that must contain lots of rare characters such as: - dropped 2 as in H20
- dropped 3 as in HC03
- The symbol for greater to or equal to, similar to > but with a dash underneath - The greek? symbol that looks like a backwards u.

Basically it must be very precise with exact chemical equations etc but I cant find how to add them anywhere as a feature in Photoshop CS. Some of them are available in Microsoft Word, but when I try to copy and paste across it doesnt work and random characters are pasted instea dof those chosen.
Any ideas?
Cheers
JO

Your subscript numbers can be done just using the Character Palette. For symbols, you may have to use the Windows Character Map, (Start > Programs > Accessories > System Tools > Character Map).

Some of them are available in Microsoft Word, but when I try to copy and paste across it doesnt work and random characters are pasted instea dof those chosen

If they are available in Word, then they should be possible in PS. There is nothing "magic" in Word.

My guess is that when you copy some text, you are using a different font in PS from what was used by Word. These special characters don't occur in all fonts.

The "backwards u" is the mu character from Greek, and will be available in the symbol font, as will the < with underline (which is less than or equal to). As mentioned, the lowered characters (which are also smaller in size) are best created as subscripts, which will help you if you get into more complex chemicals that have higher numbers, not normally available as special characters (unless perhaps in some of the new open type fonts).

Do your type in InDesign or Illustrator CS. If your font has the extended characters you can easily access them by opening the Glyphs Palette finding the symbol you want in the Glyphs palette then double clicking to add the symbol to the line of text!