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Raman spectroscopy

Once a laser illuminates on a specimen, photons of the laser beam will be absorbed by the sample and pumped to virtual states; it then reemits photons with same or slightly higher/lower frequencies and jump back to ground state. If the frequency is same, it is a Rayleigh scattering process. If the frequency is lower, it is called stock shift; otherwise it is an anti-stock shift. The frequency changes is related to the molecular vibration, rotation, bending. Therefore, similar as IR spectroscopy, Raman can also be adopted as a powerful tool to study the molecular structures.

Refractive index measurement by Abbe Refractometer

Abbe refractometer measures a material’s refractive index through determining the critical angle αc under total internal reflection conditions.

Numerical aperture and resolution

The numerical aperture of a microscope objective is the measure of its ability to gather light and to resolve fine specimen detail while working at a fixed object (or specimen) distance. Resolution of an optical microscope is defined as the smallest distance between two points on a specimen that can still be distinguished as two separate entities.

Yellowness index measurement

Yellowness Index (YI) is a number calculated from spectrophotometric data to characterize the change in color of specimen from clear or white to yellow.

Study of sub-surface features by laser confocal microscopy

A laser confocal microscope has the ability to isolate a single plane of focus from thick samples or overlapping objects. Therefore it is a powerful tool to image the surface or bulk (in transparent media) features of a specimen.

Cpm

Another type of capability index, Cpm, is much less known and used less frequently than Cpk or Ppk. The main difference between the Cpm and the other capability indices is that the bias from the target, not mean, is directly taken into consideration in the Cpm. The bias is the difference between the process average and the target.

Cp, Cpk, Pp, Ppk

Process capability, Cp, tells how well a process meets customer’s specifications. It is defined as the ratio of engineering tolerance (USL – LSL) to the natural tolerance (-3σ to 3σ) . However, a process can be capable of meeting specifications, but not be meeting specifications if the process is not centered relative to the specifications. Therefore, process capability index, Cpk, is introduced to take into account of the centeredness.

Study the curing reaction of silicone release agent through FTIR

In PSA industry, release liner is one of the key components. The main functions of release liner are to provide protection of the adhesive layer during storage and transportation, and ensure a residue-free removal from the protected adhesive layer without damaging or contaminating it.

Silicone FTIR

The paper, titled with Characterization of Surface Treatments of Cork Stoppers by FTIR-ATR and published in J. Agric. Food Chem. 2006,54, 4932-4936, proposed an analytical method for identification of the presence of surface treatments in cork stoppers. The information about the FTIR bands for silicone is quite useful.

FTIR

Molecular bonds can be considered as stiff springs which can be bent or stretched. The vibration (bending and stretching) energy lies in the infrared (IR) range. Therefore, through the interaction between IR incident beam and molecules in samples to be tested, through transmission or reflection, molecular bonds information can be extracted from the absorption spectra to obtain their molecular structures.