Re: [Phys-L] Lower limit for a slit width?

[brian whatcott <betwys1@sbcglobal.net>]

The one dimensional version of a slit is a pin hole. In this case, is 
there a limiting size for a pin hole?
I recall seeing a demonstration of a graphene surface layer on a 
transparent substrate - and the layer was all but transparent - so this 
is presumptive evidence that even the  atomic scale spacing of atomic 
sized gaps can provide a path offering  constructive interference in the 
incident direction, though the electrical conductivity in the plane of 
the surface of the graphene was much greater than silver's.

Brian Whatcott   Altus OK   Indian Country.

On 5/12/2014 11:27 AM, Savinainen Antti wrote:
> Hello,
>
> I have discussed diffraction with my HS students;  we have done some simple experiments using various diffraction gratings and laser beam. One condition for observing a diffraction pattern is that the wavelength of light (or any wave) is roughly in the same order as the slit width. If the wavelenght is much smaller than the slit width, there is no diffraction pattern (or it can be observed only at the edges). Obviously, the width can be smaller than wavelength. This prompted a question from a student:  is there a lower limit for a slit width, say, in terms of wavelenght for seeing a diffraction pattern?
>
> I think not but what do you say?
>
> Regards,
>
> Antti Savinainen
> Finland