Raman Spectroscopy Analysis Of The Gel Pen Inks Formation Time

Because of its light weight,smooth writing,inexpensive and other advantages,the Gel Pen has become the most commonly used writing instrument in People's Daily life.Correspondingly,in various criminal cases and civil cases,the inspection and identification of the color marks of the Gel Pen has become a hot spot.Some researchers have used Raman spectroscopy to study the formation time of the handwriting color marks of the Gel Pen and made some achievements.However,in the range of the laser wavelength of 785 nm,633nm and 532 nm,it is still blank to use the confocal micro-Raman spectrometer to test the writing time of natural aging continuous sample.The research content of this thesis is as follows:the best conditions of Raman spectrogram can be stimulated by black pen and blue pen,similarities and differences of Raman spectra of different brands of black pens,similarities and differences of Raman spectra of different brands of blue pens,the rule of the change of the same pen on the same paper with the writing time,and the rule of the change of the same pen on different paper with the writing time.Eighty-four different types of signature pens and five common paper are collected.Samples are made at four days interval.The experiment last 300 days.In the pre-experimental phase,83 kinds of signature pens are divided into six categories according to the characteristics of the Raman spectra.In the first category,there are 15 kinds of blue pen with seven characteristic peaks.Secondly,there is only one type of blue pen whose characteristic peak number is more than seven.The third type is the blue pen without characteristic peak,there are two kinds.The fourth type is the black pen with two characteristic peaks,there are 61 kinds.The fifth category is a black signature pen with more than two characteristic peaks,only one.The sixth category is no characteristic peak of the black pen,there are four.After using the Origin software to process the map,it is found that the first and fourth types of signature pens have a high degree of fitting and can be formally tested.In the formal experiment,the analysis of the peak area ratio of the Raman spectrum of the black pen showed that the area ratio increased with the increase of writing time;however,the analysis of the blue pen shows that two of them are enlarged.The trend,the other one shows a decreasing trend.Finally,the mathematical models between writing time and peak area ratio of black and blue signature pens are established respectively.