研究目的
To develop and characterize a cryogenic cylindrical ion trap velocity map imaging spectrometer for studying photodissociation spectroscopy and dynamics of gaseous molecular ions and ionic complexes, with a focus on achieving efficient ion cooling and minimal velocity spread.
研究成果
The developed cryogenic cylindrical ion trap velocity map imaging spectrometer effectively cools ions to low internal temperatures (~12 K rotational temperature for CO2+) and minimizes velocity spread (~±25 m/s), enabling high-resolution VMI studies of photodissociation dynamics with a resolution of Δv/v ~ 2.2%. The instrument's performance is comparable to setups for neutral molecules and provides a robust platform for investigating gaseous ions, with future work aimed at further optimizing and applying it to various ionic species.
研究不足
The instrument resolution is mainly limited by the residual radial speed spread of the parent ions after extraction from the trap, which can be affected by factors such as extraction field optimization, initial ion size, RF voltage, and residual RF fields. The cooling efficiency and velocity spread may vary for ions with different mass-to-charge ratios, requiring separate optimizations. The rotational temperature estimation is approximate due to unresolved structures and complex spectroscopic effects.
1：Experimental Design and Method Selection:
The instrument combines a cryogenically cooled cylindrical ion trap (CIT) with a velocity map imaging (VMI) spectrometer. The CIT is made of oxygen-free copper and cooled to ~7 K using a closed-cycle helium refrigerator. It is designed to trap and cool ions via collisions with a helium buffer gas, reducing internal temperatures and velocity spreads. The VMI spectrometer is used to image photofragmented ions for velocity distribution analysis.
2：Sample Selection and Data Sources:
Ions are produced by electron impact ionization of supersonic gas jets (e.g., N2, CO2/Ar mixture, pure argon). Mass selection is performed using a quadrupole mass filter. Test ions include Nx+, CO2+, Ar2+, and Ar3+.
3：3+. List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Key equipment includes a pulsed piezo-valve for gas injection, an electron gun for ionization, a quadrupole mass filter, the CIT assembly with copper electrodes and sapphire insulators, a closed-cycle helium refrigerator, RF power supply, high-voltage pulsers for ion extraction, a VMI optics assembly, an imaging detector with microchannel plates and EMCCD camera, and lasers for photodissociation. Materials include oxygen-free copper, helium buffer gas, and various gases for ion production.
4：Experimental Procedures and Operational Workflow:
Ions are generated, mass-selected, injected into the CIT, trapped and cooled for ~90 ms with helium buffer gas, extracted using synchronized high-voltage pulses, transferred to the VMI region, interacted with a laser beam for photodissociation, and imaged on the detector. Timing is controlled at 10 Hz with digital delay generators.
5：Data Analysis Methods:
Data analysis involves measuring time-of-flight spectra to assess mass resolution and ion packet size, fitting rotational temperatures from dissociation spectra using software like PGOPHER, and analyzing VMI images to determine velocity distributions and resolutions using ion trajectory simulations and calibration methods.
独家科研数据包，助您复现前沿成果，加速创新突破
获取完整内容-
EMCCD camera
iXon Ultra 888
Andor
Captures transient images from the phosphor screen for velocity map imaging.
立即获取同款设备 -
digital delay/pulse generator
DG645
SRS
Controls the timing sequence of experimental events.
暂无现货
预约到货通知
-
oscilloscope
DSOX2024A
Keysight
Digitizes time-of-flight spectra for analysis.
暂无现货
预约到货通知
-
piezo-valve
Series 9
Parker
Pulsed injection of gas mixtures into the vacuum chamber for supersonic expansion.
暂无现货
预约到货通知
-
electron gun
homemade
Generates a continuous electron beam for electron impact ionization of gas jets.
暂无现货
预约到货通知
-
quadrupole bender
Extrel
Deflects ions by 90 degrees to guide them into the quadrupole mass filter.
暂无现货
预约到货通知
-
quadrupole mass filter
QPS 500HT
Extrel
Filters ions based on mass-to-charge ratio to select specific ions for trapping.
暂无现货
预约到货通知
-
turbomolecular pump
Turbovac 450i
Leybold
Evacuates the electron impact ionization source chamber.
暂无现货
预约到货通知
-
turbomolecular pump
nEXT240D
Edwards
Evacuates the quadrupole bender chamber and VMI detection chamber.
暂无现货
预约到货通知
-
turbomolecular pump
STP301
Edwards
Evacuates the quadrupole mass filter chamber and the region containing the CIT assembly.
暂无现货
预约到货通知
-
closed cycle helium refrigerator
RDK-205D
Sumitomo
Cools the cylindrical ion trap assembly to cryogenic temperatures (~7 K).
暂无现货
预约到货通知
-
RF power supply
D-1203
R. M. Jordon
Drives the cylindrical ion trap with RF voltage for ion confinement.
暂无现货
预约到货通知
-
solenoid valve
Series 9
Parker
Pulsed introduction of helium buffer gas into the ion trap for cooling.
暂无现货
预约到货通知
-
leak valve
Series 590
VAT
Controls continuous helium flow into the ion trap for buffer gas collisions.
暂无现货
预约到货通知
-
bipolar high voltage pulser
ZKG031
NSRL
Generates push-pull type high voltage pulses for ion extraction from the trap.
暂无现货
预约到货通知
-
temperature sensor
S950
Cryocon
Measures the temperature of the CIT assembly.
暂无现货
预约到货通知
-
cartridge heater
Cryocon
Heats the CIT assembly to adjust temperature between 7 and 300 K.
暂无现货
预约到货通知
-
cryogenic grease
Apiezon N
Apiezon
Provides good thermal contact between copper constituents and sapphire plates in the CIT assembly.
暂无现货
预约到货通知
-
steering electrodes
Direct ions towards the laser interaction region in the VMI spectrometer.
暂无现货
预约到货通知
-
high voltage pulser
PVX4140
DEI
Switches the re-referencing potential for ion mass filtering and guidance.
暂无现货
预约到货通知
-
登录查看剩余18件设备及参数对照表
查看全部
