NOVELTY - The method involves providing a target made of a metal or metal-oxide material. A substrate e.g. polymer film, is provided to support the deposited particles or films of crystalline metal oxide e.g. crystalline titanium dioxide (Tio2). A set of regions of the target is ablated with a set of ultra fast laser pulses to create a plume of particles directed toward the substrate, where the ablating process produces low temperature at the substrate to avoid thermal induced alteration of a substrate property, so that a film is formed on a heat sensitive material e.g. glass.    USE - Method for depositing a nanoparticle or nanocomposite film of crystalline metal oxide e.g. crystalline titanium dioxide (Tio2), nickel oxide, zinc oxide, tin oxide, cobalt oxide or copper oxide (all claimed), onto a substrate e.g. plastic substrate, polymer film, and glass, for gas sensor, electrochromic device, dye-sensitized solar cell, and photo catalyst in a field. Uses include but are not limited to air/water purification, self-cleaning, hydrophilic/hydrophobic switching, sterilization and hydrogen production.    ADVANTAGE - The method provides one-step process to deposit nanoparticles and nanocomposite films of crystalline titanium dioxide (Ti02) at room-temperature.    DETAILED DESCRIPTION - The substrate is made of glass, paper, plastic or polymer. INDEPENDENT CLAIMS are also included for the following:    (1) an article of manufacturing having a set of instructions to perform a method for depositing nanoparticles or nanocomposite films of crystalline metal oxide onto a substrate    (2) a pulsed laser deposition system for depositing nanoparticles or nanocomposite films of crystalline metal oxide onto a substrate.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of a pulsed laser deposition system including a vacuum chamber, a target manipulator, an ion probe i.e. Langmuir probe, a gas inlet, and a substrate manipulator, where a laser beam is focused onto a target surface through a fused silica window.