Sample analysis
Scanning electron microscopy (SEM)
Scanning electron microscopy coupled with energy dispersive
X-ray analysis (EDS) (JEOL JSM-6330F, JEOL
Ltd., Akishima, Tokyo, Japan) was used for characterization,
viz. morphology (shape and size) and chemistry of
airborne particles. SEM is high-resolution surface imaging
method which uses an electron beam. The samples (dry
filter papers) were randomly cut in 1 cm2 size out of the
main filter. A very thin film of platinum (Pt) was deposited
on the surface of the samples to make them electrically
conductive. These samples were mounted on electron
microprobe stubs. The SEM–EDS analyses were carried
out with the help of a computer controlled field emission
SEM equipped with EDS detection system at the Department
of Physics, University of Pune. In the present
investigation, the SEM was used in its most common mode
i.e., emissive mode. The other parameters are as follows,
Detector: Si (Li), Limit of detection, 500,000; accuracy,
10 %; energy, 20 kV (accelerating voltages, 0.5–30 kV).
Elements with atomic number less than 6 were not determined.
Carbon and fluorine were also not considered in
present discussion due to their presence on the filter
substrate.