Schematic view of the sensor. PSD, position sensitive detector; DL, detection laser; HL, heating laser; CA, cantilever array. In the inset, a micrograph of the cantilever array is shown.
Predicted sensitivity of the cantilever in the calorimeter mode as a function of the relative thickness of the metal film: gold film (thin line), aluminum film (thick line), and a gold film with a chrome interface (dotted line). It follows from the thickness of the bare Si cantilever that optimum film thicknesses for aluminum and gold are 240 and , respectively.
Sensitivity of the cantilever as a function of the thickness of the metal film for (circles) and (triangles) cantilevers coated with gold (filled symbols) and aluminum (open symbols).
Time-dependent response of the cantilever ( long, coated with a gold film) to a laser pulse (a) in air and (b) in vacuum. It should be noted that there is a difference in the time scales between (a) and (b).
Response time (heating) of the cantilever measured in air as a function of the thickness of the gold film for (circles) and (triangles) cantilevers.
Response of the cantilever ( long, coated with a thick gold film) to pulses of neon for increasing pulse duration. The signal is typically averaged over 200–300 pulses.
Dependence of the bending rate of the cantilever on the cluster current for unselected palladium clusters with a mean size distribution of 25 atoms. The cantilever is long and coated with a thick gold film. The values of the heat rate have been corrected to take into account the heating due to the presence of the focusing octopole. In the inset, the heat rates as a function of the octopole power are depicted. Note that the power corresponds to the value set on the radio-frequency transceiver, and not to the power actually transferred to the octopole.
Thick curve: averaged response of the cantilever ( long, coated with a thick gold film), onto which 1% ML of palladium clusters has been deposited, and with an isotropic partial pressure of 1,3-butadiene of , to pulses of hydrogen (A typical flux of hydrogen under our operation conditions is per pulse). Dotted curve: averaged response of the cantilever to pulse of Ne under the same valve conditions. Hatched area: difference between the two signals. The area under the curve is proportional to the total heat released to the cantilever. For obtaining the signals 200 pulses have been averaged.
Heat of reaction per cluster and hydrogen pulse detected with the cantilever sensor as a function of the isotropic pressure of 1,3-butadiene during the hydrogenation of 1,3-butadiene on size-distributed, supported palladium clusters.
Reaction rate of the hydrogenation of 1,3-butadiene on size-distributed palladium clusters supported on measured in a separate p-MBRS setup as a function of the isotropic pressure of 1,3-butadiene; cluster coverage 1% ML.
Cantilever response of size-distributed clusters subjected to hydrogen pulses without 1,3-butadiene introduced as background gas; 2% ML cluster coverage, 200 pulses averaged.
Density , Young modulus , thermal expansion coefficient , thermal conductivity coefficient , and heat capacity per unit of mass for gold, aluminum, chrome, and silicon (Ref. 56).
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