You can determine best wavelength to ablate by measuring absorption spectrum of the material you need to ablate. Can choose the wavelength where maximum absorption occurs.

answer of deepa bhatt is almost correct but in ablation process several parameters is important such as ,cw or Q-switch laser,plasma shielding,pulse width(nanosecond or femtosecond),...if your laser is q-switch,best wavelength for ablation is lower wvelength for example uv pulse because plasma shielding is low

In order to get high production yield of nanoparticles, you must consider the conbination influence of laser intensity, pulse duration, number of pulses and pulse interval. The first factor should be femtosecond laser pulse, I think, because the ablation process has no close relation with vaporization of the material. For the propriate wavelength, as Ali Safi said before, UV pulse may be the answer.

In ruby crystal ablation we have obtained excellent results in our lab using 800nm femtosecond laser with a pulse width of 120 fs.

thank you for the brilliant comments.. I have done before and give excellent result..Unfortunatetly I don't have an further access to fs laser in my uni. Currently I'm trying to use ns laser at 532 nm but that laser can't ablate at all the ruby crystal ..

The max absorption of the crystal is at 405nm and 532 nm. However, from my reading the selection of wavelength should be at minimum absorption depth.. therefore in my understanding the wavelength should be at minimum that absorb by the crystal. Isn't it? correct me if I'm wrong..

I suggest you to used BBO to got the UV range which increase you absorption.

Did you mean the highest absorption wavelength will give highest ablation rate? However in my experience for 532 wavelength the laser beam seem like just go through the crystal without any ablation..

Yes, I expect with UV it will be highest absorption and ablation as well.

I agree with Walid, UV light allows you to get the optimal coupling efficiency from the laser pulses to the crystal structure, whereas the pulse duration will influence the size and dispersion of the nanoparticles produced. Femtosecond pulses usually induce lower size and lower dispersion in particle size. This is exactly the property used for chemical analysis through Laser Assisted Inductiveley Coupled Plasma Mass Spectrometry (LA-ICPMS). An important parameter is then the quality and the quantity required for your application...

In addition to perfect answer of "Antoine Courjaud", Also with Femtosecond , you will minimize the thermal effects and maximize the homogeneity of your nanoparticles !

laser wavelength is the important parameter.

Excimer laser it works in the UV range .... with a specific pulse repitation frequency will be helpful.

Hi

In order to ablate besides the wavelength and the absorption of the material at it you should pay attention to your energy per pulse and your focusing. I have seen ablate transparent materials in which the absorption was only 20% by focusing a laser pulse. In this case I am talking about an IR pulsed laser with about 1J per pulse but the general principle is still valid.

You may use dual pulse for ablation

You may have look to the following references for getting knowledge that, which parameters can influence the ablation rate

(1) A comparative study of single and double pulse of laser induced breakdown spectroscopy of silver

Babar Rashid, Rizwan Ahmed, Raheel Ali, MA Baig

[show abstract]

Physics of Plasmas 07/2011; 188:073301

(2) On the Optimization for Enhanced Dual-Pulse Laser-Induced Breakdown Spectroscopy

R. Ahmed, M.A. Baig

[show abstract]

IEEE Transactions on Plasma Science 09/2010.

(3)

A comparative study of single and double pulse laser induced breakdown spectroscopy

Rizwan Ahmed, M Aslam Baig

[show abstract]

Journal of Applied Physics 08/2009; 106:033307