ABSTRACT
The formation and structure of thin liquid films (TLF; such as in foams or bubbles) is a fascinating phenomena that humans have studied over many decades. This structure is the closest one comes to observing molecules with the eye. TLF is thus the thinnest object one can see without the aid of any kind of microscope. One of the most commonly known thin liquid film structures is the soap bubble or bubbles formed on detergent solutions (as in dishwashing solutions). Everyone has enjoyed this formation and its display of rainbow colors. It may look as if a bubble formation and its characteristic stability is of little consequence, but, in fact, in everyday life, bubbles play an important role (e.g., from the functioning of the lungs to the enjoyment of beer and champagne!). It is a common observation that, ordinary water, when shaken, does not form any bubbles at the surface. On the other hand, all soap and detergent solutions (shampoo, washing powder, beer, champagne, and seawater), on shaking, may form very extensive bubbles. In this chapter, the formation and stability of bubbles will be described. Further, even though one cannot see or observe the surface layer of a liquid directly, TLFs allow one to make some observations that can provide much useful information (Ivanov, 1988; Birdi, 2002).
