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There is an increasing need to characterize and identify particulate matters(PM)and biological particles suspending in air for monitoring air pollution,human health,and global climate change [1].Atmosphere contains respirable fine PM particles(with diameter of 10,or 2.5 μm or less)and biological particles(bacteria,pollen,fungi,viruses etc),which can affect the atmosphere and climate by scattering and absorbing solar radiation and play an important role in the spreading of human,animal,and plant diseases.Here,we report on the development of new methods of sampling and analysis of single atmospheric particles.Optical pulling is the transportation of a micro-particle toward to the light source along a laser pipeline,while optical trapping is the capture of a particle in an equilibrium position.Radiation pressure and gradient force have been used to levitate and trap the transparent particles in air.However,photophoretic force can be several orders of magnitude larger than the radiation force for absorbing particles and thus prevents the use of radiation forces for stable trapping [2].In addition,radiation force is generally pointing to the laser propagation direction and thus prevents pulling a particle toward to the light source.Here,we will describe the use of negative photophoretic forces that are induced by the momentum transfer between the aerosol particles and surrounding gas molecules to pull and trap single micron-sized absorbing particles and biological particles in air environment.We show that the particles can be pulled over a meter or longer distance with a speed of 1-10 cm/s and they are observed to rotate around the beam axis at 0.2-20 kHz.The pulled particles can be collected and identified with Raman spectroscopy [1,4].We measure the circular motion of single optically trapped absorbing particles with a focused Gaussian beam and observe the centripetal acceleration of the trapped particle as high as~20 times the gravitational acceleration.We will also report on the use of a rubidium(Rb)vapor as an ultra-narrow notch filter for ultralow frequency Stokes and anti-Stokes Raman spectroscopy of single optically trapped living cells and micro-sized particles with a frequency shift down to 10 cm-1 [3].This work was supported by a grant from the US Army Research Office.