Title page for ETD etd-1003102-092130

Document Type thesis

Author Name Thoreson, Erik J.

URN etd-1003102-092130

Title Apparatus to Deliver Light to the Tip-sample Interface of an Atomic Force Microscope (AFM)

Degree MS

Department Physics

Advisors
N. A. Burnham, Advisor

Keywords
purple membrane
photomechanics
photoinduced conformation change
photocycle
photoactive
bacteriorhodopsin
photoinduced
bimetallic bending
atomic force microscope
tip-sample interface
molecular conformation
PLDS
photoreactive
AFM

Date of Presentation/Defense 2002-08-26

Availability unrestricted

Abstract
An apparatus for the delivery of radiation to the tip-sample interface of an Atomic Force Microscope (AFM) is demonstrated. The Pulsed Light Delivery System (PLDS) was fabricated to probe photoinduced conformational changes of molecules using an AFM. The PLDS is 67 mm long, 59 mm wide, and 21 mm high, leaving clearance to mount the PLDS and a microscope slide coated with a thin film of photoactive molecules beneath the cantilever tip of a stand-alone AFM. The PLDS is coupled into a fiber pigtailed Nd:Yag frequency doubled laser, operating at a wavelength of 532 nm. The radiation delivered to a sample through the PLDS can be configured for continuous or pulsed mode. The maximum continuous wave (CW) power delivered was 0.903 mW and the minimum pulse width was 12.3 ms (maximal 401 ms), corresponding to a minimal energy of 0.150 nJ (maximal 362 nJ), and had a cycle duration of 10.0 ms. The PLDS consists of micro-optical components 3.0 mm and smaller in diameter. The optical design was inspired by the three-beam pick-up method used in CD players, which could provide a method to focus the pulse of light onto the sample layer. In addition, the system can be easily modified for different operational parameters (pulse width, wavelength, and power). As proof that the prototype design works, we observed a photoinduced ‘bimetallic’ bending of the cantilever, as evidenced by observing no photoinduced bending when a reflective-coated cantilever was replaced by an uncoated cantilever. Using the apparatus will allow investigation of many different types of molecules exhibiting photoinduced isomerization.

Files
thoreson.pdf

Browse by Author | Browse by Department | Search all available ETDs

Questions? Email etd-questions@wpi.edu
Maintained by webmaster@wpi.edu

Document Type	thesis
Author Name	Thoreson, Erik J.
URN	etd-1003102-092130
Title	Apparatus to Deliver Light to the Tip-sample Interface of an Atomic Force Microscope (AFM)
Degree	MS
Department	Physics
Advisors	N. A. Burnham, Advisor
Keywords	purple membrane photomechanics photoinduced conformation change photocycle photoactive bacteriorhodopsin photoinduced bimetallic bending atomic force microscope tip-sample interface molecular conformation PLDS photoreactive AFM
Date of Presentation/Defense	2002-08-26
Availability	unrestricted
Abstract An apparatus for the delivery of radiation to the tip-sample interface of an Atomic Force Microscope (AFM) is demonstrated. The Pulsed Light Delivery System (PLDS) was fabricated to probe photoinduced conformational changes of molecules using an AFM. The PLDS is 67 mm long, 59 mm wide, and 21 mm high, leaving clearance to mount the PLDS and a microscope slide coated with a thin film of photoactive molecules beneath the cantilever tip of a stand-alone AFM. The PLDS is coupled into a fiber pigtailed Nd:Yag frequency doubled laser, operating at a wavelength of 532 nm. The radiation delivered to a sample through the PLDS can be configured for continuous or pulsed mode. The maximum continuous wave (CW) power delivered was 0.903 mW and the minimum pulse width was 12.3 ms (maximal 401 ms), corresponding to a minimal energy of 0.150 nJ (maximal 362 nJ), and had a cycle duration of 10.0 ms. The PLDS consists of micro-optical components 3.0 mm and smaller in diameter. The optical design was inspired by the three-beam pick-up method used in CD players, which could provide a method to focus the pulse of light onto the sample layer. In addition, the system can be easily modified for different operational parameters (pulse width, wavelength, and power). As proof that the prototype design works, we observed a photoinduced ‘bimetallic’ bending of the cantilever, as evidenced by observing no photoinduced bending when a reflective-coated cantilever was replaced by an uncoated cantilever. Using the apparatus will allow investigation of many different types of molecules exhibiting photoinduced isomerization.
Files	thoreson.pdf