  Laser ablation through liquid is an important process that have to be studied
for applications which use laser ablation in liquid (LAL) and laser shock
peening (LSP). LAL is employed for production of suspensions of nanoparticles,
while LSP is applied to increase hardness and fatique/corrosion resistance
properties of a surface layer. A bubble appears in liquid around the laser spot
focused at a target surface after strong enough laser pulse. In the paper we
connect the early quasi-plane heated layer created by a pulse in liquid and the
bubble forming at much later stages. In the previous works these early stage
from one side and the late stage from another side existed mainly as
independent entities. At least, quantitative links between them were unknown.
We consider how the quasi-plane heated layer of liquid forms thank to thermal
conduction, how gradually conduction becomes weaker, and how the heated layer
of liquid nearly adiabatically expands to few orders of magnitude in volume
during the drop of pressure. Our molecular dynamics simulations show that the
heated layer is filled by the diffusive atomic metal-liquid mixture. Metal
atoms began to condense into nanoparticles (NP) when they meet cold liquid
outside the edge of a mixing zone. This process limits diffusive expansion of
metal atoms, because diffusive ability of NP is less than this ability for
individual atoms. Thus the mixture expands together with hot liquid, and the
NPs approximately homogeneously fill an interior of a bubble.
